Alkenes as alkyne equivalents in radical cascades terminated by fragmentations
09708351 ยท 2017-07-18
Assignee
Inventors
- Igor V. Alabugin (Tallahassee, FL, US)
- Sayantan Mondal (Tallahassee, FL, US)
- Rana K. Mohamed (Tallahassee, FL, US)
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International classification
C07C67/333
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Abstract
Disclosed are methods for rerouting radical cascade cyclizations by using alkenes as alkyne equivalents. The reaction sequence is initiated by a novel 1,2 stannyl shift which achieves chemo- and regioselectivity in the process. The radical hopping leads to the formation of the radical center necessary for the sequence of selective cyclizations and fragmentations to follow. In the last step of the cascade, the elimination of a rationally designed radical leaving group via -CC bond scission aromatizes the product without the need for external oxidant. The Bu.sub.3Sn moiety, which is installed during the reaction sequence, allows further functionalization of the product via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.
Claims
1. A method of synthesizing a Sn-functionalized aromatic compound comprising a fused aromatic ring system, the method comprising contacting a stannane compound and a reactant compound having the following structure (I)-a: ##STR00110## wherein: each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkoxy, amino, and phenyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted; and wherein the Sn-functionalized aromatic compound comprising a fused aromatic ring system has the following structure (IV)-b: ##STR00111## wherein: each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted; and each R.sub.5 independently comprises alkyl, aryl, or heteroaryl.
2. The method of claim 1 wherein X is selected from the group consisting of hydroxyl and amine.
3. The method of claim 1 wherein Ar is substituted with an alkenyl, an alkynyl, or both an alkenyl and an alkynyl.
4. The method of claim 1 wherein the reactant compound has the following structure (I)-a: ##STR00112## wherein: each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl and amine; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
5. The method of claim 1 wherein the reactant compound has any of the following structures (III)-a, (III)-b, and (III)-c: ##STR00113## wherein: X is selected from the group consisting of hydroxyl, alkoxy, amino, and phenyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
6. The method of claim 1 further comprising contacting the Sn-functionalized aromatic compound comprising a fused aromatic ring system with an acid to thereby prepare a substituted naphthalene having the structure (V)-b: ##STR00114## wherein: each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
7. The method of claim 1 further comprising contacting the Sn-functionalized aromatic compound comprising a fused aromatic ring system with an organic precursor compound to prepare a substituted naphthalene having the structure (VI)-b: ##STR00115## wherein: each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted; and R.sub.6 is selected from the group consisting of alkyl, aryl, heteroaryl, amino, alkoxy, and halo.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION
(14) While investigating the scope of enyne cyclizations, we observed that alkyl substitution at the alkene changes the regioselectivity of the cyclization, directing the formation of a 6-endo product 2 in 65% yield. See
(15) However, we also observed a small amount of naphthalene byproduct 3, aromatized by the loss of an alkyl group. See
(16) The feasibility of the fragmentation pathway is largely rationalized by the aromatic stabilization gained in the conversion of the initial 6-endo-trig products into naphthalene derivatives. The fragmentation is further enhanced by stabilizing the departing radical fragment via the rational design of radical leaving groups (LG). A balance between stability and reactivity is crucial because the reactivity of radicals formed in fragmentations dictates the outcome of the competition between propagation and termination of radical cascades. In particular, reactive radicals can react further in an undesirable way. We aimed to design the cascade such that the balance between stability and reactivity is struck, resulting in the sole formation of naphthalene derivatives. We found that this is possible upon altering the alkene substituent to CH.sub.2XCH.sub.3, where XO or NMe. See
(17) 2-Center, 3-electron (2c-3e) delocalization between the alkyl radical center and lone pair of the adjacent heteroatom serves to stabilize the radical leaving group effectively allowing the cascade to self-terminate. This term was introduced by Wille et al. to describe transformations where stable fragmenting radicals exit the reaction without exhibiting subsequent reactivity. See References 22 and 23. Such 2c-3e interactions correspond to the formal bond order of and can be referred to as half-bonds. Their presence accounts for the observed increase in the yield of naphthalene derivatives from enynes incorporating this rational design.
(18) Accordingly, the present invention is directed to a method of synthesizing compounds comprising fused aromatic ring systems. Stated another way, in some embodiments, the method of the present invention involves a cyclization reaction of a starting material comprising an aromatic ring, e.g., a benzene ring, substituted with an alkene and an alkyne. The alkene further comprises a rationally designed radical leaving group which is eliminated from the product via CC bond scission. This last step aromatizes the product without the need for external oxidant. The use of rationally designed alkenes successfully overcomes restrictions which had previously inhibited formal access to a synthetically valuable cyclization mode. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.
I. Definitions
(19) It is noted that, as used in this specification and the intended claims, the singular form a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a compound includes a single compound as well as one or more of the same or different compounds.
(20) As used in the specification and the appended claims, unless specified to the contrary, the following terms have the meaning indicated:
(21) The term alkyl, as used herein, means a straight or branched, saturated hydrocarbon chain containing from 1 to 12 carbon atoms, such as from 1 to 10 carbon atoms, such as from 1 to 8 carbon atoms, or from 1 to 6 carbon atoms. In some embodiments, an alkyl comprises a straight or branched, saturated hydrocarbon chain containing from 1 to 6 carbon atoms. The term C.sub.x-C.sub.y alkyl means a straight or branched chain, saturated hydrocarbon containing x to y carbon atoms. For example C.sub.1-C.sub.6 alkyl means a straight or branched chain, saturated hydrocarbon containing 1 to 6 carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 2,2-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, 2-methylheptyl, 3-methylheptyl, 2,3-dimethylheptyl, isooctyl, n-nonyl, and n-decyl, n-undecyl, n-dodecyl, etc.
(22) The term alkylene, as used herein, means a divalent group derived from a straight or branched, saturated hydrocarbon chain of 1 to 10 carbon atoms, for example, of 1 to 8 carbon atoms, or of 1 to 6 carbon atoms. The term C.sub.1-C.sub.6 alkylenyl, as used herein, means a divalent group derived from a straight or branched, saturated hydrocarbon chain of 1 to 6 carbon atoms. Examples of an alkylene include, but are not limited to, CH.sub.2, C(H)(CH.sub.3), CH.sub.2CH.sub.2, CH.sub.2CH.sub.2CH.sub.2, CH.sub.2CH(CH.sub.3), CH.sub.2CH.sub.2CH.sub.2CH.sub.2, CH.sub.2CH(CH.sub.3)CH.sub.2, and CH.sub.2C(CH.sub.3).sub.2CH.sub.2.
(23) The term alkenyl, as used herein, means a straight or branched hydrocarbon chain containing from 2 to 10 carbons and containing at least one carbon-carbon double bond. In some embodiments, alkenyl may comprise a straight or branched hydrocarbon chain containing from 2 to 6 carbons and containing at least one carbon-carbon double bond. The term C.sub.2-C.sub.4 alkenyl means an alkenyl group containing 2-4 carbon atoms. Non-limiting examples of alkenyls include buta-2,3-dienyl, ethenyl, 2-propenyl, 2-methyl-2-propenyl, 3-butenyl, 4-pentenyl, 5-hexenyl, 2-heptenyl, 2-methyl-1-heptenyl, and 3-decenyl. An alkenyl group may be unsubstituted, or it may be substituted with hydroxyl, alkyl, alkoxy, cycloalkyl, heterocyclic, amino, aryl, heteroaryl, and benzyl.
(24) The term alkenylene, as used herein, means a divalent group derived from a straight or branched chain hydrocarbon of 2 to 4 carbon atoms and contains at least one carbon-carbon double. Representative examples of alkenylene include, but are not limited to, CHCH and CH.sub.2CHCH.
(25) The term alkynyl, as used herein, means a straight or branched chain hydrocarbon group containing from 2 to 10 carbon atoms and containing at least one carbon-carbon triple bond. The term C.sub.2-C.sub.4 alkynyl, as used herein, means an alkynyl group containing from 2 to 4 carbon atoms. Representative examples of alkynyl include, but are not limited, to acetylenyl, 1-propynyl, 2-propynyl, 3-butynyl, 2-pentynyl, 1-butynyl, and 2-butynyl. An alkynyl group may be unsubstituted or it may be substituted with aryl or heteroaryl.
(26) The term alkoxy, as used herein, means a straight or branched, saturated hydrocarbon chain containing from 1 to 12 carbon atoms, such as from 1 to 6 carbon atoms and O terminating the hydrocarbon chain. The term C.sub.x-C.sub.y alkoxy, as used herein, means a straight or branched chain, saturated hydrocarbon containing x to y carbon atoms and O terminating the hydrocarbon chain. For example C.sub.1-C.sub.6 alkoxy means a straight or branched chain, saturated hydrocarbon containing 1 to 6 carbon atoms and O terminating the hydrocarbon chain. Examples of an alkoxy include, but are not limited to, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, sec-butoxy, iso-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, n-hexoxy, 2-methylpentoxy, and 2,2-dimethylbutoxy.
(27) In the context of the present specification, unless otherwise stated, a hydroxyalkyl substituent group or a hydroxyalkyl moiety in a substituent group may be linear or branched. Examples of C.sub.1-6 hydroxyalkyl groups/moieties include methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, etc, each of which comprises at least one hydroxyl group substituent in place of a hydrogen.
(28) In the context of the present specification, amine or amino encompasses all primary (one alkyl group), secondary (two alkyl groups), tertiary (three alkyl groups), or quaternary amine (four alkyl groups). The alkyl groups are defined as above. Exemplary amines include tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, triethylamine, diethylamine, ethylamine and the like. Other representative organic amines include ethylenediamine, ethanolamine, diethanolamine, piperidine, piperazine and the like.
(29) In the context of the present invention, aryl or aromatic encompasses aromatic rings, which may be fused or unfused to other aromatic or cycloalkyl rings. Aryl or aromatic encompasses aromatic rings (i.e., comprising carbon and hydrogen). Aryl may comprise from 3 to 24 carbon atoms, such as from 6 to 24 carbon atoms. Examples of aryl include benzene, naphthalene, acenaphthene, anthracene, benz[a]anthracene, benzo[a]pyrene, benzo[e]pyrene, chrysene, indeno(1,2,3-cd)pyrene, phenanthrene, pyrene, coronene, fluorene, and the like.
(30) The term aryl, as used herein, means a phenyl or a bicyclic aryl. The bicyclic aryl may be naphthyl, or a phenyl fused to a monocyclic cycloalkyl, or a phenyl fused to a monocyclic cycloalkenyl. Non-limiting examples of the aryl groups include phenyl, dihydroindenyl (e.g. 2,3-dihydro-1H-inden-1-yl), indenyl, naphthyl, dihydronaphthalenyl, and tetrahydronaphthalenyl (e.g. 1,2,3,4-tetrahydronaphthalen-1-yl). The aryl groups can be unsubstituted or substituted, e.g., with alkyl, halo, haloalkyl, alkoxy, cyano, heterocyclo, etc., and the bicyclic aryl is attached to the parent molecular moiety through any substitutable carbon atom contained within the bicyclic ring system.
(31) The term cycloalkyl or cycloalkane, as used herein, means a monocyclic or a bicyclic ring system. The term monocyclic cycloalkyl, as used herein, is a carbocyclic ring system containing three to eight carbon atoms, such as three to six carbon atoms, zero heteroatoms and zero double bonds. Examples of monocyclic ring systems include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The bicyclic cycloalkyl is a monocyclic cycloalkyl fused to a monocyclic cycloalkyl ring. The monocyclic or bicyclic cycloalkyl ring may contain one or two alkylene bridges, each consisting of one, two, three, or four carbon atoms, each linking two non-adjacent carbon atoms of the ring system. Non-limiting examples of such bridged cycloalkyl ring systems include bicyclo[3.1.1]heptane, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane, bicyclo[3.2.2]nonane, bicyclo[3.3.1]nonane, bicyclo[4.2.1]nonane, tricyclo[3.3.1.0.sup.3,7]nonane (octahydro-2,5-methanopentalene or noradamantane), and tricyclo[3.3.1.1.sup.3,7]decane (adamantane). The monocyclic and the bicyclic cycloalkyls can be unsubstituted or substituted, e.g., with alkyl, halo, haloalkyl, alkoxy, cyano, heterocyclo, etc., and are attached to the parent molecular moiety through any substitutable atom contained within the ring system.
(32) The term cycloalkenyl or cycloalkene, as used herein, means a monocyclic or a bicyclic hydrocarbon ring system. The monocyclic cycloalkenyl has four, five, six, seven, eight, nine, or ten carbon atoms, e.g., C.sub.4-C.sub.10, or C.sub.5-C.sub.10 cycloalkenyl, and zero heteroatoms. The four-membered ring systems have one double bond, the five- or six-membered ring systems have one or two double bonds, and the seven- or eight-membered ring systems have one, two, or three double bonds. Representative examples of monocyclic cycloalkenyl groups include, but are not limited to, cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclononenyl, cyclodecenyl. The bicyclic cycloalkenyl is a monocyclic cycloalkenyl fused to a monocyclic cycloalkyl group, or a monocyclic cycloalkenyl fused to a monocyclic cycloalkenyl group. The monocyclic or bicyclic cycloalkenyl ring may contain one or two alkylene bridges, each consisting of one, two, three, or four carbon atoms, each linking two non-adjacent carbon atoms of the ring system. Representative examples of the bicyclic cycloalkenyl groups include, but are not limited to, 4,5,6,7-tetrahydro-3aH-indene, octahydronaphthalenyl, and 1,6-dihydro-pentalene. The monocyclic and bicyclic cycloalkenyl can be unsubstituted or substituted, e.g., with alkyl, halo, haloalkyl, alkoxy, cyano, heterocyclo, etc., and are attached to the parent molecular moiety through any substitutable atom contained within the ring systems, and can be unsubstituted or substituted.
(33) The term halo or halogen or halide, as used herein, means Cl, Br, I, or F.
(34) The term haloalkyl, as used herein, means an alkyl group, as defined herein, in which one, two, three, four, five or six hydrogen atoms are replaced by halogen. The term C.sub.1-C.sub.6 haloalkyl, as used herein, means a C.sub.1-C.sub.6 alkyl group, as defined herein, in which one, two, three, four, five, or six hydrogen atoms are replaced by halogen. The term C.sub.1-C.sub.4 haloalkyl, as used herein, means a C.sub.1-C.sub.4 alkyl group, as defined herein, in which one, two, three, four, five, or six hydrogen atoms are replaced by halogen. Representative examples of haloalkyl include, but are not limited to, chloromethyl, fluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, trifluoromethyl, difluoromethyl, pentafluoroethyl, 2-chloro-3-fluoropentyl, trifluorobutyl (such as, but not limited to, 4,4,4-trifluorobutyl), and trifluoropropyl (such as, but not limited thereto, 3,3,3-trifluoropropyl).
(35) The term haloaryl, as used herein, means a phenyl or bicyclic aryl in which one, two, three, four, five, six, seven, or eight hydrogen atoms are replaced by halogen. Non-limiting examples of the aryl groups include fluorophenyl, chlorophenyl, bromophenyl, iodophenyl, fluoro-, chloro-, bromo-, or iodo-dihydroindenyl (e.g. 2,3-dihydro-1H-inden-1-yl), fluoro-, chloro-, bromo-, or iodo-indenyl, fluoro-, chloro-, bromo-, or iodo-naphthyl, fluoro-, chloro-, bromo-, or iodo-dihydronaphthalenyl, and fluoro-, chloro-, bromo-, or iodo-tetrahydronaphthalenyl (e.g. 1,2,3,4-tetrahydronaphthalen-1-yl).
(36) The term heterocycle or heterocyclic, as used herein, means a monocyclic heterocycle or a bicyclic heterocycle. The monocyclic heterocycle, as used herein, is a three-, four-, five-, six-, seven-, eight-, nine-, or ten-membered ring containing at least one heteroatom independently selected from the group consisting of O, N, and S. The three-, four-, five-, six-, seven-, eight-, nine-, or ten-membered ring contains zero or one double bond, and one heteroatom selected from the group consisting of O, N, and S. The four-, five-, six-, seven-, eight-, nine-, or ten-membered heterocyclic ring contains zero or one double bond, and one heteroatom selected from the group consisting of O, N, and S. The five-membered ring contains zero or one double bond and one, two, or three heteroatoms selected from the group consisting of O, N, and S. The six-membered ring contains zero, one, or two double bonds and one, two, or three heteroatoms selected from the group consisting of O, N, and S. The seven- and eight-membered rings contains zero, one, two, or three double bonds and one, two, or three heteroatoms selected from the group consisting of O, N, and S. Non-limiting examples of monocyclic heterocycles include azetidinyl, azepanyl, aziridinyl, diazepanyl, 1,3-dioxanyl, 1,3-dioxolanyl, 1,3-dithiolanyl, 1,3-dithianyl, imidazolinyl, imidazolidinyl, isothiazolinyl, isothiazolidinyl, isoxazolinyl, isoxazolidinyl, morpholinyl, oxadiazolinyl, oxadiazolidinyl, oxazolinyl, oxazolidinyl, oxetanyl, piperazinyl, piperidinyl, pyranyl, pyrazolinyl, pyrazolidinyl, pyrrolinyl, pyrrolidinyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydrothienyl, thiadiazolinyl, thiadiazolidinyl, thiazolinyl, thiazolidinyl, thiomorpholinyl, 1,1-dioxidothiomorpholinyl (thiomorpholine sulfone), thiopyranyl, and trithianyl. The bicyclic heterocycle, as used herein, is a monocyclic heterocycle fused to a phenyl group, or a monocyclic heterocycle fused to a monocyclic cycloalkyl, or a monocyclic heterocycle fused to a monocyclic cycloalkenyl, or a monocyclic heterocycle fused to a monocyclic heterocycle. Non-limiting examples of bicyclic heterocycles include e.g. dihydrochromenyl (e.g. 3,4-dihydro-2H-chromen-4-yl), benzopyranyl, benzothiopyranyl, 2,3-dihydrobenzofuranyl, 2,3-dihydrobenzothienyl, and 2,3-dihydro-1H-indolyl. The monocyclic and the bicyclic heterocycles may contain an alkenylene bridge of two, three, or four carbon atoms, or one or two alkylene bridges of 1, 2, 3, or 4 carbon atoms, or combinations thereof, wherein each bridge links two non-adjacent atoms of the ring system. Non-limiting examples of such bridged heterocycles include octahydro-2,5-epoxypentalene, azabicyclo[2.2.1]heptyl (including 2-azabicyclo[2.2.1]hept-2-yl), hexahydro-2H-2,5-methanocyclopenta[b]furan, hexahydro-1H-1,4-methanocyclopenta[c]furan, aza-admantane (1-azatricyclo[3.3.1.1.sup.3,7]decane), and oxa-adamantane (2-oxatricyclo[3.3.1.1.sup.3,7]decane). In some embodiments, a 4- to 10-membered ring heterocyclyl may be selected from among 2,3-dihydrofuranyl, 2,5-dihydrofuranyl, tetrahydrofuranyl, 1,3-dioxolanyl, 1,3-dioxanyl, tetrahydro-2H-pyranyl, 3,4-dihydro-2H-pyranyl, 3,6-dihydro-2H-pyranyl, 2H-pyranyl, 4H-pyranyl, pyrrolidinyl, 2,3-dihydro-1H-pyrrolyl, 2,5-dihydro-1H-pyrrolyl, 4H-1,3-dioxinyl, 1,4-dioxanyl, 2,3-dihydro-1,4-dioxinyl, piperidinyl, 2-oxa-7-azaspiro[3.5]nonanyl, 1,2-dihydropyridinyl, 1,4-dihydropyridinyl, 2,3-dihydropyridinyl, 3,4-dihydropyridinyl, 1,2,3,6-tetrahydropyridinyl, isoxazolidinyl, oxazolidinyl, 2,3-dihydroisoxazolyl, 2,5-dihydroisoxazolyl, and morpholino, each of which may be substituted or unsubstituted. The monocyclic and the bicyclic heterocycles can be unsubstituted or substituted, e.g., with alkyl, halo, haloalkyl, alkoxy, cyano, heterocyclo, cycloalkyl, sulfonyl, etc., and are connected to the parent molecular moiety through any substitutable carbon atom or any substitutable nitrogen atom contained within the rings. The nitrogen and sulfur heteroatoms in the heterocycle rings may optionally be oxidized and the nitrogen atoms may optionally be quaternized.
(37) The term heteroaryl, as used herein, means a monocyclic heteroaryl or a bicyclic heteroaryl. The heteroaryl may comprise 5- to 10-membered ring. The monocyclic heteroaryl is a five- or six-membered ring. The five-membered ring contains two double bonds. The five membered ring may contain one heteroatom selected from O or S; or one, two, three, or four nitrogen atoms and optionally one oxygen or one sulfur atom. The six-membered ring contains three double bonds and one, two, three or four nitrogen atoms. Representative examples of monocyclic heteroaryl include, but are not limited to, furanyl, imidazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, 1,3-oxazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrazolyl, pyrrolyl, tetrazolyl, thiadiazolyl, 1,3-thiazolyl, thienyl, triazolyl, and triazinyl. The bicyclic heteroaryl consists of a monocyclic heteroaryl fused to a phenyl, or a monocyclic heteroaryl fused to a monocyclic cycloalkyl, or a monocyclic heteroaryl fused to a monocyclic cycloalkenyl, or a monocyclic heteroaryl fused to a monocyclic heteroaryl, or a monocyclic heteroaryl fused to a monocyclic heterocycle. Non-limiting examples of bicyclic heteroaryl groups include benzofuranyl, benzothienyl, benzoxazolyl, benzimidazolyl, benzoxadiazolyl, 6,7-dihydro-5H-cyclopenta[b]pyridinyl (e.g. 6,7-dihydro-5H-cyclopenta[b]pyridin-7-yl), 6,7-dihydro-1,3-benzothiazolyl, imidazo[1,2-a]pyridinyl, indazolyl, indolyl, isoindolyl, isoquinolinyl, naphthyridinyl, pyridoimidazolyl, quinolinyl, thiazolo[5,4-b]pyridin-2-yl, thiazolo[5,4-d]pyrimidin-2-yl, and 5,6,7,8-tetrahydroquinolinyl (e.g. 5,6,7,8-tetrahydroquinolin-5-yl, 5,6,7,8-tetrahydroquinolin-8-yl). In some embodiments, 5- to 10-membered ring heteroaryl may be selected from among pyridinyl, pyrimidinyl, pyrazinyl, 1H-indolyl, 2H-indolyl, pyrazolyl, 1H-imidazolyl, oxazolyl, isoxazolyl, pyrazolyl, quinolinyl, isoquinolinyl, furo[3,2-b]pyridinyl, furo[4,3-b]pyridinyl, furo[5,4-b]pyridinyl, and benzo[c][1,2,5]oxadiazol-5-yl, each of which may be substituted or unsubstituted. The monocyclic and bicyclic heteroaryl groups can be substituted, e.g., with alkyl, halo, haloalkyl, alkoxy, cyano, heterocyclo, cycloalkyl, sulfonyl, etc., or unsubstituted and are connected to the parent molecular moiety through any substitutable carbon atom or any substitutable nitrogen atom contained within the ring systems.
(38) The term heteroatom, as used herein, means a nitrogen, oxygen, or sulfur atom.
(39) The term oxo, as used herein, means a O group.
(40) The term carbonyl, as used herein, means a
(41) ##STR00002##
group. A carbonyl group may alternatively be disclosed as C(O).
(42) The term carboxy or carboxyl, as used herein, means a
(43) ##STR00003##
group. A carboxy or carboxyl group may alternatively be disclosed as C(O)O.
(44) The term hydroxy or hydroxyl, as used herein, means a OH group. In some embodiments, a hydroxy or hydroxyl group may be bonded to an alkyl thereby forming an hydroxyalkyl, such as, but not limited to hydroxymethyl, hydroxyethyl, etc.
(45) The term cyano, as used herein, means a CN group.
(46) The term imino, as used herein, means a
(47) ##STR00004##
group. The imino may be bonded to one, two, or three groups, such as, but not limited to, alkyl, hydroxyl, alkoxy.
(48) The term thio, as used herein, means a group comprising a S group.
(49) The term sulfonyl, as used herein, means a group comprising a
(50) ##STR00005##
group.
(51) The term phosphate, as used herein, means a PO.sub.3H.sub.2 group. One or both hydrogens in a phosphate may be replaced with cations, such as sodium or potassium.
II. Synthesis
(52) In some embodiments, the method of the present invention is directed to the synthesis of a polycyclic aromatic compound, e.g., a naphthalene derivative. In some embodiments, the method of the present invention is directed to synthesizing a Sn-functionalized aromatic compound comprising a fused aromatic ring system. The Sn-functionalized aromatic compound may be contacted with acid to thereby remove the Sn-moiety and prepare a substituted naphthalene compound. Alternatively, the Sn-functionalized aromatic compound comprising a fused aromatic ring system may be contacted with other organic compounds to incorporate further functionality onto the fused aromatic ring system.
(53) According to some embodiments, the method comprises contacting a stannane compound, e.g., a tin hydride, and a reactant compound having the following structure (I):
(54) ##STR00006##
(55) In some embodiments, the reaction mixture further comprises a radical initiator. In some embodiments, the reaction may occur in a solvent, such as an aprotic solvent. Accordingly, in some embodiments, the reaction mixture comprises a compound having the structure (I), a stannane compound, and a radical initiator. Contact of these components may occur in a solvent, such as an aprotic solvent.
(56) In some embodiments, each of R.sub.a, R.sub.b, R.sub.c, and R.sub.d are independently carbon or nitrogen. In some embodiments, each of R.sub.a, R.sub.b, R.sub.c, and R.sub.d are carbon. In some embodiments, at least two of R.sub.a, R.sub.b, R.sub.c, and R.sub.d are carbon, and the remainder are nitrogen. In some embodiments, three of R.sub.a, R.sub.b, R.sub.c, and R.sub.d are carbon, and one is nitrogen.
(57) In some embodiments, each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, halogen, cyano, amino, alkyl, alkoxy, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system. In some embodiments, each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system.
(58) In some embodiments, the X is selected from the group consisting of hydroxyl, alkyl, alkoxy, cycloalkyl, heterocyclic, amino, aryl, heteroaryl, and benzyl. In some embodiments, the X moiety is selected from the group consisting of hydroxyl, alkoxy, amino, and phenyl. In some embodiments, the X moiety may be unsubstituted, such as hydroxyl or amine (NH.sub.2). In some embodiments, the X moiety may comprise a substituted alkoxy, a substituted amino, or a substituted phenyl. Suitable substituents include aryl, alkyl, halo, and amino.
(59) In the above compound having structure (I), Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted. Suitable substituents include alkyl, alkenyl, alkynyl, halo, cyano, carbonyl, alkoxy, aryl (e.g., an additional ring or a fused aromatic ring), among others. In some embodiments, the Ar group is substituted with reactive alkene moieties and reactive alkyne moieties.
(60) In some embodiments, the reactant compound has the following structure (I)-a:
(61) ##STR00007##
wherein each of R.sub.1 R.sub.2, R.sub.3, R.sub.4, X, and Ar are as defined above in connection with structure (I).
(62) In some embodiments of the compound of structure (I)-a, each of R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, halogen, cyano, amino, alkyl, alkoxy, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkyl, alkoxy, cycloalkyl, heterocyclic, amino, aryl, heteroaryl, and benzyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
(63) In some embodiments of the compound of structure (I)-a, each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkoxy, amino, phenyl, and benzyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
(64) In some embodiments, the reactant compound has any of the following structures (I)-b, (I)-c, (I)-d, or (I)-e:
(65) ##STR00008##
wherein each of R.sub.1 R.sub.2, R.sub.3, R.sub.4, X, and Ar are as defined above in connection with structure (I).
(66) In some embodiments of the compound of any of the structures (I)-b, (I)-c, (I)-d, or (I)-e, each of R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, halogen, cyano, amino, alkyl, alkoxy, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkyl, alkoxy, cycloalkyl, heterocyclic, amino, aryl, heteroaryl, and benzyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
(67) In some embodiments of the compound of any of the structures (I)-b, (I)-c, (I)-d, or (I)-e, each R.sub.1 R.sub.2, R.sub.3, and R.sub.4 independently comprises hydrogen, alkenyl, alkynyl, aryl, or any two adjacent R.sub.1 R.sub.2, R.sub.3, and R.sub.4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkoxy, amino, phenyl, and benzyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.
(68) In some embodiments, the Ar group is substituted with reactive alkene moieties and reactive alkyne moieties. Still further configurations are possible, e.g., if the Ar group is substituted with reactive alkene and alkyne moieties. In some embodiments, the reactant compound may have the following structures (II)-a, (II)-b, (II)-c, or (II)-d:
(69) ##STR00009##
(70) Each of the R.sub.1 R.sub.2, R.sub.3, R.sub.4, X, and Ar are as defined above in connection with structure (I). Such compounds are capable of preparing substituted naphthalene compounds linked by a bond or an intervening functional group.
(71) Still further configurations are possible, such as the following compounds having structures (III)-a, (III)-b, and (III)-c in which a core benzene ring is substituted with two or three alkenyl moieties and two or three alkynyl moieties:
(72) ##STR00010##
(73) Each of the X and Ar are as defined above in connection with structure (I).
(74) Still further examples of reactant compounds are provided in the Examples.
(75) In some embodiments, the stannane compound, e.g., a tin hydride, has a general formula X.sub.3SnH, wherein X is a C.sub.1-C.sub.6 alkyl or phenyl. In some embodiments, the stannane compound is selected from the group consisting of trimethyl stannane, triethyl stannane, tri(n-propyl) stannane, tri(isopropyl) stannane, tri(n-butyl) stannane, tri(isobutyl) stannane, triphenyl stannane, and any combination there. The identity of X in structure (1-a) is determined primarily, if not wholly, by the stannane compound. In some preferred embodiments, the stannane compound is tri(n-butyl) stannane. In general, the stannane compound may be contacted with the reactant compound in relatively equivalent molar amounts, such as in a molar ratio of stannane compound to reactant compound between about 1:2 and about 3:1, such as between about 1:1 and about 2:1, such as about 1.2:1.
(76) In some embodiments, the radical initiator is any compound that can provide radicals for the initiation step of a radical chain reaction. In some embodiments, the radical initiator is any compound that converts the stannane compound (generally, X.sub.3SnH, wherein X is a C.sub.1-C.sub.6 alkyl or phenyl) into X.sub.3Sn radical. Suitable radical initiators include azo compounds, inorganic peroxides, or organic peroxides. In some embodiments, the radical initiator is Azobisisobutyronitrile (2,2-azobis(2-methylpropionitrile), AIBN). In some embodiments, the radical initiator is 1,1-Azobis(cyclohexanecarbonitrile) (ABCN). In some embodiments, the radical initiator is di-tert-butyl peroxide (TOOT, or DTBPB). In some embodiments, the radical initiator is benzoyl peroxide. The radical initiator may be added to the reaction mixture in less than molar equivalent amount of the radical initiator compared to the reactant compound, such as a molar ratio less than 1:1, or less than about 1:2 (i.e., about 0.5 molar equivalents per 1 molar reactant compound), or less than about 1:4.
(77) The contact may occur in a solvent, suitably an aprotic solvent. Solvents suitable for the reaction of the present invention include benzene, diethyl ether, toluene, tetrahydrofuran, hexane, and dichloromethane. In some preferred embodiments, the solvent is toluene or benzene, with toluene being particularly preferred.
(78) In some embodiments, contact between the reactant compound and the stannane compound yields a Sn-functionalized aromatic compound comprising a fused aromatic ring system having the following structure (IV)-a:
(79) ##STR00011##
(80) wherein each of R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.1 through R.sub.4 and Ar are as defined above in connection with Structure (I). Each R.sub.5 independently comprises alkyl, aryl, or heteroaryl. Preferably, each R.sub.5 independently comprises alkyl.
(81) In some embodiments, contact between the reactant compound and the stannane compound yields a Sn-functionalized aromatic compound comprising a fused aromatic ring system having the following structure (IV)-b:
(82) ##STR00012##
(83) wherein R.sub.1 through R.sub.4 and Ar are as defined above. Each R.sub.5 independently comprises alkyl, aryl, or heteroaryl. Preferably, each R.sub.5 independently comprises alkyl.
(84) According to some embodiments of the present invention, the Sn-functionalized aromatic compound comprising a fused aromatic ring system is further contacted with an acid to remove the Sn moiety. Contact with an acid thereby prepares a substituted naphthalene having the structure (V)-a:
(85) ##STR00013##
(86) wherein each of R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.1 through R.sub.4 and Ar are as defined above in connection with Structure (I). Suitable acids include any inorganic or mineral acid, such as hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, and the like.
(87) According to some embodiments of the present invention, the Sn-functionalized aromatic compound comprising a fused aromatic ring system is further contacted with an acid to remove the Sn moiety. Contact with an acid thereby prepares a substituted naphthalene having the structure (V)-b:
(88) ##STR00014##
(89) R.sub.1 through R.sub.4 and Ar are as defined above. Suitable acids include any inorganic or mineral acid, such as hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, and the like.
(90) Still further products may be prepared according to the present invention, as disclosed in the Examples.
(91) According to some embodiments of the present invention, the Sn-functionalized aromatic compound comprising a fused aromatic ring system is subjected to further functionalization. Accordingly, in some embodiments, the Sn-functionalized aromatic compound may be contacted with organic precursor compounds sufficient to prepare a substituted naphthalene having the structure (VI)-a:
(92) ##STR00015##
(93) wherein each of R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.1 through R.sub.4 and Ar are as defined above in connection with Structure (I). R.sub.6 is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, amino, alkoxy, and halo.
(94) According to some embodiments of the present invention, the Sn-functionalized aromatic compound comprising a fused aromatic ring system is subjected to further functionalization. Accordingly, in some embodiments, the Sn-functionalized aromatic compound may be contacted with organic precursor compounds sufficient to prepare a substituted naphthalene having the structure (VI)-b:
(95) ##STR00016##
(96) R.sub.1 through R.sub.4 and Ar are as defined above. R.sub.6 is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, amino, alkoxy, and halo.
(97) In some embodiments, functionalization of products having structures (IV)-a and (IV)-b may be carried out by the Stille reaction in which the Sn(R.sub.5).sub.3 group is replaced with an organic functionality by contacting the compound having structure (IV)-a or (IV)-b with an organic halide. The Stille reaction is catalyzed by a Pd.sup.0 compound, such as tetrakis(triphenylphosphine) palladium(0). The Examples provide several reactions proceeding occurring to the Stille reaction.
(98) In some embodiments, functionalization of products having structures (IV)-a and (IV)-b may be carried out by Sonogashira coupling in which the Sn(R.sub.5).sub.3 group is replaced with a leaving group, such as iodo, bromo, chloro, or triflate. The Sonogashira coupling is catalyzed by a palladium catalyst and a copper catalyst. The Sonogashira coupling of the product compounds enables functionalization with an alkynyl compound. The Examples provide several reactions proceeding occurring to Sonogashira coupling.
(99) In some embodiments, functionalization of products having structures (IV)-a and (IV)-b may be carried out by the Suzuki reaction in which the Sn(R.sub.5).sub.3 group is replaced with a leaving group, such as iodo, bromo, chloro, or triflate. The Suzuki reaction is catalyzed by a palladium catalyst. The Suzuki reaction of the product compounds enables functionalization through single bonds. The Examples provide several reactions proceeding occurring to the Suzuki reaction.
III. Design of Radical Leaving Groups
(100) In order to break unstrained CC bonds under relatively mild conditions, both thermodynamics and kinetics of this process need to be optimized. See Reference 7. In the present example, the energetic penalty for the homolytic cleavage of a strong CC bond is partially compensated by the aromatic stabilization gained in the product. However, the 2.sup.nd product (the propyl radical) is a high energy, unstable species. We envisioned that stabilization of the alkyl radical would further promote the fragmentation. See
(101) Radical fragmentations provide a valuable option for the termination of cascade transformations. See Reference 9. The reactivity of radicals formed in the fragmentation step dictates the outcome of the competition between propagation and termination of radical cascades. Our design of stabilized radical leaving groups was guided by the electronic structure of super-stable radicals, i.e., molecular oxygen, nitric oxide, and TEMPO, where a half-filled orbital is stabilized by an adjacent lone pair. In the extreme, such strong 2-center, 3-electron (2c-3e) interactions correspond to the bond order of and can be referred to as half-bonds. Stabilization provided by the 2c-3e interactions depends on the relative electronegativity of the heteroatom.
(102) We expected that such strong stabilization via incorporation of heteroatoms adjacent to the radical center will increase the efficiency of the self-terminating fragmentation and also render the fragmented radical relatively inert, preventing undesirable side reactions. Allylic oxygen, nitrogen, and aromatic substituents can be easily incorporated at the ene terminus using well established CC coupling procedures, affording the requisite set of substrates. See
(103) To our delight, heteroatom incorporation completely switched the selectivity in favor of the self-terminating fragmentation. See
(104) The self-terminating nature of the fragmentation is supported by the need to use stoichiometric amount of initiator (0.5 equiv. AIBN produces 1 equiv. of isobutyronitrile radical) for full conversion. See Table 1. While bond dissociation energies (BDE) suggest propagation via hydrogen abstraction by .CH.sub.2X from Bu.sub.3SnH to be a thermodynamically favorable process (HCH.sub.2OH, BDE=96 kcal/mol vs. Bu.sub.3SnH, BDE=74 kcal/mol), kinetics of such a process may be relatively slow as both species are nucleophilic. See reference 11.
(105) TABLE-US-00001 TABLE 1 Optimization of equivalents of AIBN..sup.[a] Unreacted Bu.sub.3SnH AIBN SM.sup.[b] (equiv.) (equiv.) Time (h) Yield.sup.[b] (%) (%) 1D 1.2 0.1 12 11 42 1D 1.2 0.2 12 31 19 1D 1.2 0.2 12 10.sup.[c] 24 1D 1.2 0.4 12 65 9 1D 1.2 0.5 12 78 0 .sup.[a]See FIG. 7 for reaction conditions. .sup.[b]Determined by Ph.sub.3CH internal standard. .sup.[c]With 0.2 eq. PhSH
(106) We envisioned that the fragmented radical could be coerced into propagating the radical chain via polarity reversal catalysis. See Reference 10. In such processes, H-atom transfer between two nucleophilic radicals is promoted via an H-shuttle with an electrophilic radical.
(107) However, our attempt at increasing the efficiency of propagation steps using thiophenol as the H-shuttle decreased the napthalene yield. See Table 1, entry 3. While 10% of 3 was formed (along with 24% of the reactant), we also obtained significant amounts of reduced acyclic products. Product 3 is derived from the least stable of equilibrating radicals, suggesting the radical pool can be depleted if the more stable radicals (incapable of cyclization) find a suitable reaction path. This is consistent with the previous reports of polarity reversal catalysts prematurely terminating radical cascades by trapping relatively unreactive intermediates. See Reference 12.
(108) Another possibility preventing propagation is the facility of further fragmentation of the CH.sub.2XR radical. See Reference 13. We are currently investigating the mechanistic details in hopes of obtaining fragmented species and finding conditions for efficient propagation.
IV. Computational Analysis
(109) Further insights into electronic factors responsible for the facile fragmentations came from DFT calculations. Free energies (G) of fragmentation were negative due to combination of radical stabilization and the favorable entropic contribution. Because nitrogen is a better donor than oxygen and because lone pairs are better donors than CH/CC bonds, we expected reaction energies to reflect the importance of donor abilities of lone pairs in the stabilization of the fragmented radical in the order analogous to that in
V. Through-Bond Interactions in Odd Electron Systems
(110) Such electronic effects are well-known when both of the non-bonding orbitals are singly occupied (i.e., in 1,4-diradicals). In these systems, through-bond coupling of radical centers increases population of the * bridge orbital, ultimately leading to fragmentation into two 2-center, 2-electron bonds (2c-2e). See Reference 16. The same effect is responsible for rendering the Bergman cyclization a symmetry-allowed reaction and providing ca. 3-5 kcal/mol stabilization to p-benzyne. See References 17 and 18. Symmetry-enforced TB interactions play an important role in aborted sigmatropic shifts, an unusual class of pericyclic reactions where geometry corresponding to the cyclic TS is more stable than the acyclic reactants. See Reference 8c. However, the role of TB coupling between radical centers and lone pairs in 2c-3e systems is not commonly recognized, perhaps due to the decreased driving force for the fragmentation of monoradicals, where one of the formed bonds is the 2c-3e half-bond. See
VI. Increased TB Interaction in the Fragmentation TS
(111) Reactant stabilization is a potentially counterproductive factor in the design of fragmentations. However, the surprisingly large magnitude of kinetic effects on the calculated activation energies in
(112) In order to differentiate thermodynamic contributions to the barrier (the consequence of the increased stability of reaction products) from stabilizing effects intrinsic to the transition state (Equation 1), we turned to Marcus theory. See Reference 20. This approach dissects reaction energy as a combination of intrinsic energy and thermodynamic contribution as described in Eq. 1.
E.sup.=E.sub.0.sup.+E.sub.rxn+E.sup.2.sub.rxn/16(E.sub.0.sup.)Eq. (1)
(113) Stereoelectronic differences in the TS can be identified by examining the intrinsic barrier (E.sub.0.sup.), i.e., the barrier of a thermoneutral process lacking the thermodynamic contributions. See Reference 21. The intrinsic barrier can be estimated when both the activation and reaction energies are known. See
(114) Based on the Marcus model, one would expect that the effect on the activation barrier should be significantly smaller than effect on the reaction energy (G.sup.G). Contrary to these expectations the effect on G.sup. rivals the effect on G in the case of XCH.sub.2NMe.sub.2. The relatively small and sometimes negative activation entropies are surprising for a fragmentation reaction, suggesting an increased degree of structural organization in the TS. In order to eliminate the complication associated with the difference in the entropic penalties, we focused our attention on reaction energies (E) and discovered even more striking trends (e.g., E.sup.=22.0 with E=21.4 kcal/mol, respectively, for 1A vs. 1E. These surprising observations suggest that the stabilizing effect of the heteroatom starts to manifest itself before a radical center is fully developed at the adjacent carbon.
(115) The intrinsic reaction barriers are given in
(116) These large effects on the fragmentation barrier originate from an electronic communication between the non-bonding orbitals that weakens the bridging -bond in the TS. See
(117) The final computational evidence was provided by Natural Bond Orbital (NBO) analysis of the initial radical, transition state, and half-bonded radical fragments that revealed the presence of very strong stabilizing interactions between radical, lone pair of oxygen, and the bridge orbitals. See Table 2.
(118) TABLE-US-00002 TABLE 2 NBO analysis at the UM062X/LanL2DZ level of theory. Interaction energies in kcal/mol. SM TS.sup.[a] Interaction -spin -spin -spin -spin n.sub.C .fwdarw. *.sub.C-C 5.9 1.7 89.6 13.4 n.sub.O .fwdarw. *.sub.C-C 3.9 4.9 2.7 30.7 .sub.C-C .fwdarw. n.sub.C 5.0 79.9 .sup.[a]The given Lewis structure was obtained using the $CHOOSE keyword. Indicates the interaction is less than the threshold of 0.5 kcal/mol.
(119) While communication through the a-bridge is present in the radical, the effects become much larger in the TS. The increase in interactions can be understood from the second order perturbation energies provided by NBO analysis (Equation 2).
(120)
(121) During fragmentation the energy of the a-bonding orbital is raised as the * is lowered, decreasing the E.sub.ij term for interactions with non-bonding orbitals (i.e., the radical and lone pair). In addition, as the fragmentation progresses, the sp.sup.3 -bond is transformed into two p-orbitals (one -bonded in naphthalene and the other in a 2c-3e half-bond), increasing overlap between interacting orbitals. Together these interactions are responsible for selective TS stabilization for the fragmentation process.
VII. Practical Applications: Access to Extended Polyaromatics
(122) For convenience, we usually remove the Bu.sub.3Sn moiety by protodestannylation of the reaction mixtures prior to purification. However, the Sn moiety in the indene and naphthalene products can be retained and utilized as a useful functionality for further synthetic transformations. In particular, Stille coupling and iodination of the -Sn-substituted naphthalene confirmed the direction of tin attack and presented a synthetic advantage for facile functionalization of naphthalene cores. Both approaches provided highly substituted naphthalene derivatives that are otherwise difficult to prepare from the parent aromatic core, shown in
(123) As noted above, changing the alkyne substituent in simple enynes, from benzene to naphthalene or anthracene decreases the product yield. We attribute this decrease to an increase in steric congestion during the intramolecular attack of the vinyl radical on the alkene (compounds K33 and K34). The stabilizing effect of conjugating substituents for the unproductive Bu.sub.3Sn attack at the external alkyne (and, possibly, alkene) positions pose limitations that are illustrated by unsuccessful attempts to directly access triphenylene derivatives from the cyclization of enyne P7 shown in
(124) To test the validity of the above assumption, we moved conjugating substituents to the outside aryl group where they would stabilize the productive radicals. To our delight, we found that, with this structural change, the reaction successfully gives bis- and tris-naphthalene substituted biphenyl compounds P4 and P6 in excellent yield. See
(125) Furthermore, such products can serve as a convenient launching point for the preparation of extended polyaromatics. See
(126) The present work describes a radical cascade which self-terminates via expulsion of primary C-centered radicals. Even though the energetic penalty for the homolytic cleavage of a strong CC bond is significant, the combination of two stabilizing effects (the aromatic stabilization gained in the product and stabilization of radical leaving groups with 2c-3e bonds) can compensate for the cost of CC bond cleavage. In the reaction sequence, a radical center is relocated to a position where it can communicate with a donor lone pair through a CC bridge (TB interaction). Such communication leads to selective TS stabilization for the CC bond cleavage. This work illustrates the potential of 2c-3e interactions in the design of radical leaving groups. Incorporation of CC bond cleavage into self-terminating radical cascades allows the use of alkenes as alkyne equivalents for the preparation of aromatic structures.
EXAMPLES
(127) The following non-limiting examples are provided to further illustrate the present invention.
Example 1. General Procedures
(128) Toluene and THF were obtained from Glass Contour Solvent Purification System. Hexanes for column chromatography and preparatory thin layer chromatography were distilled prior to use. All other solvents were used as purchased. Column chromatography was performed using silica gel (60 ) and Preparatory thin layer chromatography was performed using a 1000 m glass backed plate containing UV dye. Unless otherwise noted, .sup.1H NMRs were run on 400 MHz and 600 MHz spectrometer in CDCl.sub.3 and .sup.13C NMR were run on 100 MHz and 150 MHz spectrometer in CDCl.sub.3. Proton chemical shifts are given relative to the residual proton signal of CDCl.sub.3 (7.26 ppm). Carbon chemical shifts were internally referenced to CDCl.sub.3 (77.23 ppm) signal. All J-coupling values are reported in Hertz (Hz).
Example 2. Cyclization Reaction
(129) The starting enyne (0.34 mmol) was degassed in 4 mL of toluene and heated to reflux. Two separate solutions of AIBN (0.5 eq.) and Bu.sub.3SnH (1.2 eq.) each in 3 mL toluene were added using syringe pump through the top of a condenser over the course of 4 hours into the refluxing solution. The reaction was allowed to stir at reflux. Reaction progress was monitored by TLC. After completion, the solvent was evaporated and the product was dissolved in 20 mL DCM and washed with a 1M HCl. The product was purified on silica gel using a gradient of ethyl acetate:hexane as eluent.
Example 3. Scheme A: Procedure for Synthesis of Compound 1A
(130) ##STR00017##
(131) Preparation of Wittig SaltButyltriphenylphosphonium Iodide
(132) Butyl iodide (2 g, 10.8 mmol) was added dropwise into a solution of triphenylphosphine (7 g, 10.8 mmol) in toluene in a pressure tube at room temperature. It was stirred for 48 hours at 120 C. The separated solid was filtered through a Buchner funnel and the residue was washed with petroleum ether. The resulting white solid was recrystallized from distilled petroleum ether (60-80 C.). Yield: 97%.
(133) Wittig Reaction
(134) n-BuLi (3 mL of a 1.5M solution in Hexane, 3.0 mmol) was added slowly to a solution of Wittig salt from butyl iodide (3.5 mmol) in anhydrous THF (10 mL) at room temperature. After 30 min, a solution of 2-bromobenzaldehyde (3.5 mmol) in THF (10 mL) was added dropwise. The resulting solution was allowed to stir at room temperature for 12 h and quenched with saturated NH.sub.4Cl solution. The aqueous phase was extracted with Et.sub.2O (330 mL), and the combined organic layers were washed with brine, dried over anhydrous Na.sub.2SO.sub.4, and evaporated under reduced pressure. The crude mixture was purified by column chromatography (hexane) on silica gel affording A1 (70%) as colorless oil.
(135) Sonogashira Cross Coupling of Aryl Bromide Al with Phenylacetylene (1A):
(136) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2 (PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of phenylacetylene (5.4 mmol) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under educed pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compound 1A (90%).
Compound A1: 1-bromo-2-(pent-1-en-1-yl)benzene (Mixture of Z and E (3:2))
(137) ##STR00018##
(138) Chromatographic purification (hexane) afforded compound 1A (70% yield) as a yellow oil. Rf=0.6 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.59 (d, J=8.0 Hz), 7.55-7.49 (m), 7.32-7.23 (m), 7.13-7.04 (m), 6.64 (d, J=15.7 Hz), 6.48 (d, J=11.5 Hz), 6.19 (td, J=15.7, 7.0 Hz), 5.80 (td, J=11.5, 7.4 Hz), 2.26 (dq, J=7.4, 1.2 Hz), 2.18 (dq, J=7.4, 1.7 Hz), 1.57-1.42 (m), 1.0 (t, J=7.4 Hz), 0.93 (t, J=7.4 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 137.9, 134.2, 134.1, 133.0, 132.7, 130.8, 129.0, 128.7, 128.3, 127.5, 127.0, 124.2, 123.3, 35.4, 30.6, 23.0, 22.6, 14.0, 13.9. HRMS (EI): calcd for C.sub.11H.sub.13Br [M]+224.0201, found 224.0198. IR (neat, cm.sup.1): 3022, 1499, 1020.
Compound 1A: 1-(pent-1-en-1-yl)-2-(phenylethynyl)benzene (Mixture of Z and E (3:2))
(139) ##STR00019##
(140) Chromatographic purification (hexane) afforded compound 1A (90% yield) as a yellow oil. Rf=0.6 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.66-7.59 (m), 7.50-7.46 (m), 7.45-7.36 (m), 7.33-7.29 (m), 7.28-7.25 (m), 7.15-7.06 (m), 7.11 (t, J=16.9 Hz), 6.90 (d, J=11.7 Hz), 6.50-6.40 (m), 5.90 (td, J=11.7, 7.3 Hz), 2.40-2.33 (m), 1.66-1.54 (m), 1.08 (t, J=7.4 Hz), 1.03 (t, J=7.4 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 141.4, 139.8, 139.6, 134.1, 133.1, 132.6, 132.4, 131.7, 129.3, 129.0, 128.9, 128.8, 128.6, 128.5, 128.4, 128.3, 128.2, 128.0, 127.7, 126.6, 126.5, 124.9, 123.7, 122.8, 121.9, 121.3, 108.3, 99.9 (2C), 88.6, 88.4, 35.6, 31.0, 23.2, 22.6, 14.0. HRMS (ED: calcd for C.sub.19H.sub.18[M]+246.1409, found 246.1400. IR (neat, cm.sup.1): 3024, 1491, 1069.
Example 4. Scheme B: Procedure for Synthesis of Compound (1B)
(141) ##STR00020##
(142) Sonogashira Cross Coupling of 2-bromobenzaldehyde with Phenylacetylene (B1):
(143) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2(PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of phenylacetylene (5.4 mmol) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds B1 (95%).
(144) Wittig Reaction
(145) To a solution of the Wittig salt from iodomethane (3.5 mmol) in anhydrous THF (10 mL) at 78 C. was added slowly n-BuLi (3 mL of a 1.5M solution in hexane, 3.0 mmol). After 45 min, a solution of B1 (3.5 mmol) in THF (10 mL) was added dropwise. The resulting solution was stirred for 40 min at 78 C. Then, the reaction mixture was allowed to reach room temperature and quenched with saturated NH.sub.4Cl solution. The aqueous phase was extracted with Et.sub.2O (330 mL), and the combined organic layers were washed with brine, dried over anhydrous Na.sub.2SO.sub.4, and evaporated under reduced pressure. The crude was purified by column chromatography (hexane) on silica gel affording 1B (90%) as a yellow oil.
Compound 1B: 1-(phenylethynyl)-2-vinylbenzene
(146) ##STR00021##
(147) Chromatographic purification (hexane) afforded compound 1B (90% yield) as a yellow oil. Rf=0.6 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.65 (1H, d, J=8.1 Hz), 7.63-7.56 (3H, m), 7.42-7.33 (5H, m), 7.27 (1H, dt, J=7.5, 1.1 Hz), 5.91 (1H, d, J=17.6 Hz), 5.45 (1H, d, J=11.0 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 139.2, 135.1, 132.7, 131.7 (2C), 128.6, 128.5 (3C), 127.7, 124.9, 123.5, 122.1, 115.8, 94.2, 87.9. HRMS (EI): calcd for C.sub.16H.sub.12 [M]+204.0939, found 204.0936. IR (neat, cm.sup.1): 3059, 2213, 1490, 898.
Example 5. Scheme C: General Procedure for Synthesis of Compounds 1C-1D
(148) ##STR00022##
(149) Preparation of Wittig SaltEthyl (Triphenylphosphoranylidene) Acetate:
(150) Ethyl bromoacetate (2.9 mL, 26.7 mmol) was added dropwise into a solution of triphenylphosphine (7 g, 26.7 mmol) in benzene at room temperature. It was stirred for 4-5 hours. The separated solid was filtered through a Buchner funnel and the residue was washed with hexane. The resulting white solid was taken in benzene (200 mL) and 15 g sodium hydroxide in 100 mL of water. It was stirred until both layers became clear. The benzene layer was taken out, dried over sodium sulfate and concentrated. The white salt was recrystallized from distilled petroleum ether (60-80 C.). Yield: 96%.
(151) Wittig Reaction (C1):
(152) Ethyl (triphenylphosphoranylidene) acetate (2.80 g, 8.17 mmol) was added to a solution of bromobenzaldehyde (1.0 g, 5.4 mmol) in dry DCM (dichloromethane) at 0 C. and stirred for 8 hours at room temperature. The solvent was then evaporated under vacuum. The colorless oil was partitioned between ethyl acetate and water. The organic layer was washed with water, brine and dried over Na.sub.2SO.sub.4. It was then filtered and evaporated to give an oil from which the title compound C1 was isolated by column chromatography (Si-gel, PE:EA=15:1). Yield: 95%; State: colorless oil.
(153) DIBAL-H Reduction of ,-Unsaturated Ester C1(C2):
(154) A THF solution of compound C1 (2.0 g, 7.8 mmol) was cooled to 0 C. Diisobutylaluminum hydride (DIBAL-H, 1.0M in hexane, 15 ml, 15 mmol) was slowly added to this solution under a nitrogen atmosphere and was stirred for 6 h. The reaction was quenched with aq. NH.sub.4Cl sol. (20 ml) and extracted with ethyl acetate (100 ml). The extract was washed with brine solution, dried over MgSO.sub.4, and concentrated under reduced pressure. The residue was eluted through a silica column to afford C2 as a colorless oil (92%).
(155) Methylation of 2-bromocinnamyl alcohol C2 (C3):
(156) To a suspension of NaH (60% dispersion in mineral oil) in THF (20 mL) was added 2-bromocinnamyl alcohol C2 (1.0 g, 4.7 mmol) at room temperature. The mixture was stirred for 100 min at room temperature, after which MeI (0.9 ml, 14 mmol, 3 equiv) was added in one portion. The mixture was stirred for 1 h at room temperature, then filtrated through a pad of silica gel. The solid was washed using hexane/ethyl acetate (1:1) as the eluent, and the filtrate was concentrated and purified by silica gel column chromatography, using 5% ethylacetate in hexane as the eluent, to afford the title compound C3 (96% yield) as colorless oil.
(157) Sonogashira Cross Coupling of Aryl Bromides (C2, C3) with Phenylacetylene (1C-1D):
(158) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2(PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of phenylacetylene (5.4 mmol) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds 1C-1D in 96-95% yields.
Compound 1C: (E)-3-(2-(phenylethynyl)phenyl)prop-2-en-1-ol
(159) ##STR00023##
(160) Chromatographic purification (5% ethyl acetate in hexane) afforded compound 1C (96% yield) as a brown solid; m.p. 59 C.; Rf=0.6 (5% ethyl acetate in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.58-7.53 (4H, m), 7.38-7.34 (3H, m), 7.30 (1H, t, J=7.4 Hz), 7.25-7.22 (1H, m), 7.20 (1H, d, J=15.9 Hz), 6.48 (1H, td, J=15.9, 5.7 Hz), 4.38 (2H, dd, J=5.7, 1.3 Hz), 1.73 (1H, bs). .sup.13C NMR (150 MHz; CDCl.sub.3) 138.2, 132.6, 131.6 (2C), 130.8, 128.8, 128.6, 128.5 (2C), 128.4, 127.3, 125.2, 123.3, 121.9, 94.1, 87.9, 63.7. HRMS (ED: calcd for C.sub.17H.sub.14O [M]+234.1045, found 234.1039. IR (neat, cm.sup.1): 3325 (b), 3056, 2856, 1491.
Compound C3: (E)-1-bromo-2-(3-methoxyprop-1-en-1-yl)benzene
(161) ##STR00024##
(162) Chromatographic purification (5% ethyl acetate in hexane) afforded compound C3 (96% yield) as a colorless oil. Rf=0.5 (3% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.54 (2H, dt, J=7.9, 1.1 Hz), 7.26 (1H, t, J=7.6 Hz), 7.09 (1H, dt, J=7.7, 1.5 Hz), 6.80 (1H, d, J=15.8 Hz), 6.22 (1H, td, J=15.8, 5.6 Hz), 4.12 (2H, dd, J=5.9, 1.4 Hz), 3.41 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 136.8, 133.1, 131.3, 129.2, 129.1, 127.7, 127.3, 123.8, 73.1, 58.3. HRMS (ED: calcd for C.sub.10H.sub.11BrO [M]+225.9993, found 225.9989. IR (neat, cm.sup.1): 3055, 1440, 1113.
Compound 1D: (E)-1-(3-methoxyprop-1-en-1-yl)-2-(phenylethynyl)benzene
(163) ##STR00025##
(164) Chromatographic purification (5% ethyl acetate in hexane) afforded compound 1D (95% yield) as a brown oil. Rf=0.6 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.61-7.54 (4H, m), 7.41-7.36 (3H, m), 7.31 (1H, t, J=7.6 Hz), 7.26-7.20 (2H, m), 6.41 (1H, td, J=16.0, 6.0 Hz), 4.18 (2H, dd, J=6.0, 1.1 Hz), 3.43 (3H, s).). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.3, 132.7, 131.7 (2C), 130.7, 128.7, 128.6, 128.5 (2C), 128.1, 127.5, 125.4, 123.5, 122.1, 94.2, 88.0, 73.4, 58.2. HRMS (ED: calcd for C.sub.18H.sub.16O [M]+248.1201, found 248.1200. IR (neat, cm.sup.1): 3055, 2214, 1489, 965.
Example 6. Scheme D: Procedure for Synthesis of Compound 1E
(165) ##STR00026##
(166) Iodination of Alcohol 1C (D1):
(167) A DCM solution of compound 1C (0.5 g, 2.13 mmol) was cooled to 0 C. Triphenylphosphine (0.61 g, 2.35 mmol), iodine (0.59 g, 2.35 mmol), and imidazole (0.29 g, 4.26 mmol) were slowly added to this solution. After stirring at 0 C. for 2 h, the reaction was quenched with water and extracted with ethyl acetate (50 ml). The extract was washed with brine solution, dried over MgSO4, and concentrated under reduced pressure. The residue was eluted through a silica column to afford compound D1 (75%) as darkbrown solid.
(168) Allylic Substitution Reaction of D1 with Pyrrolidine (1E):
(169) A DCM solution of compound D1 (0.5 g, 2.13 mmol) was cooled to 0 C. Pyrrolidine (0.59 g, 2.35 mmol), was slowly added to this solution and it was stirred at room temperature for 6 h. The reaction was quenched with water and extracted with ethyl acetate (50 ml). The extract was washed with brine solution, dried over MgSO4, and concentrated under reduced pressure. The residue was eluted through a silica column with 15% ethyl acetate in hexane to afford compound 1E (95%) as dark green oil.
Compound D1: (E)-1-(3-iodoprop-1-en-1-yl)-2-(phenylethynyl)benzene
(170) ##STR00027##
(171) Chromatographic purification (hexane) afforded compound D1 (75% yield) as a dark brown solid; m.p. 63 C.; Rf=0.3 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.60-7.52 (4H, m), 7.42-7.37 (3H, m), 7.31 (1H, dt, J=7.6, 1.5 Hz), 7.24 (1H, dt, J=7.5, 1.4 Hz), 7.18 (1H, d, J=15.6 Hz), 6.57 (1H, td, J=15.6, 8.2 Hz), 4.18 (2H, dd, J=8.2, 1.0 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 137.4, 132.9, 131.8 (2C), 131.2, 128.9, 128.7 (2C), 128.6 (2C), 128.0, 125.5, 123.4, 122.3, 94.6, 87.7, 7.0. HRMS (EI): calcd for C.sub.17H.sub.13I [M]+344.0062, found 344.0054. IR (neat, cm.sup.1): 3015, 2923, 1490, 1135, 958.
Compound 1E: (E)-1-(3-(2-(phenylethynyl)phenyl)allyl)pyrrolidine
(172) ##STR00028##
(173) Chromatographic purification (15% ethyl acetate in hexane) afforded compound 1E (95% yield) as a dark green oil. Rf=0.5 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.58-53 (3H, m), 7.51 (1H, dd, J=7.5, 1.1 Hz), 7.38-7.33 (3H, m), 7.30-7.26 (1H, m), 7.20 (1H, dt, J=7.5, 1.2 Hz), 7.13 (1H, d, J=15.9 Hz), 6.43 (1H, td, J=15.9, 6.7 Hz), 3.33 (2H, dd, J=6.7, 1.3 Hz), 2.61-2.57 (4H, m), 1.82-1.79 (4H, m). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.8, 132.6, 131.6 (2C), 130.0, 129.8, 128.6, 128.5 (2C), 128.4, 127.2, 125.1, 123.5, 121.8, 94.0, 88.1, 58.7, 54.2 (2C), 23.6 (2C). HRMS (EI): calcd for C.sub.21H.sub.21N[M]+ 287.1674, found 287.1679. IR (neat, cm.sup.1): 3057, 2959, 2783, 1491, 966.
Example 7. Scheme E: Procedure for Synthesis of Compound 1F
(174) ##STR00029##
(175) Preparation of Wittig SaltPhenethyltriphenylphosphoniumbromide
(176) (2-bromoethyl)benzene (10.0 mmol) was added dropwise into a solution of triphenylphosphine (10.0 mmol) in toluene in a pressure tube at room temperature. It was stirred for 48 hours at 120 C. The separated solid was filtered through a Buchner funnel and the residue was washed with hexane. The resulting white solid was recrystallized from distilled petroleum ether (60-80 C.). Yield: 91%.
(177) Wittig Reaction
(178) To a solution of the Wittig salt from (2-bromoethyl)benzene (3.5 mmol) in anhydrous THF (10 mL) at 78 C. was added slowly n-BuLi (3 mL of a 1.5M solution in hexane, 3.0 mmol). After 30 min, a solution of 2-bromobenzaldehyde (3.5 mmol) in THF (10 mL) was added dropwise. The resulting solution was stirred for 1 h at 78 C. and then at room temperature for 12 h and quenched with saturated NH.sub.4Cl solution. The aqueous phase was extracted with Et.sub.2O (330 mL), and the combined organic layers were washed with brine, dried over anhydrous Na.sub.2SO.sub.4, and evaporated under reduced pressure. The crude was purified by column chromatography (hexane) on silica gel affording E1 (E:Z=1:4, 83%) as colorless oil.
(179) Sonogashira Cross Coupling of Aryl Bromide E1 with Phenylacetylene(1F):
(180) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2(PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of phenylacetylene (5.4 mmol) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds 1F (95%).
Compound E1: 1-bromo-2-(3-phenylprop-1-en-1-yl)benzene
(181) ##STR00030##
(182) Chromatographic purification (hexane) afforded compound E1 (78% yield) as a colorless oil.; Rf=0.4 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.61 (dd, J=8.0, 1.0 Hz), 7.54-7.48 (m), 7.34-7.28 (m), 7.23-7.20 (m), 7.13 (dt, J=7.8, 1.8 Hz), 7.07 (dt, J=7.8, 1.6 Hz), 6.82 (d, J=15.6 Hz), 6.62 (d, J=11.3 Hz), 6.29 (td, J=15.6, 7.0 Hz), 5.98 (td, J=11.3, 7.6 Hz), 3.64 (d, J=7.0 Hz), 3.52 (d, J=7.6 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 140.4, 137.4, 133.0, 132.8, 132.4, 131.8, 130.6, 130.1, 129.8, 128.8, 128.7, 128.6, 128.5, 127.6, 127.1, 126.5, 126.3, 124.3, 39.6, 34.6. HRMS (EI): calcd for C.sub.15H.sub.13Br[M]+ 272.0201, found 272.0198. IR (neat, cm.sup.1): 3058, 1490.
Compound 1F: 1-(phenylethynyl)-2-(3-phenylprop-1-en-1-yl)benzene
(183) ##STR00031##
(184) Chromatographic purification (hexane) afforded compound 1F (78% yield) as a colorless oil.; Rf=0.4 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.62-7.61 (m), 7.58-7.56 (m), 7.54 (d, J=7.7 Hz), 7.51-7.49 (m), 7.45 (d, J=7.7 Hz), 7.43-7.36 (m), 7.35-7.31 (m), 7.29-7.27 (m), 7.24-7.20 (m), 7.04 (d, J=15.8 Hz), 6.96 (d J=11.4 Hz), 6.53 (td, J=15.8, 6.8 Hz), 6.03 (td, J=11.4, 7.6 Hz), 3.67 (d, J=7.6 Hz), 3.65 (d, J=7.4 Hz), .sup.13C NMR (150 MHz; CDCl.sub.3) 140.8, 139.3, 132.7, 132.5, 131.9, 131.8, 131.7, 131.5, 129.3, 129.1, 129.0, 128.9, 128.7 (2C), 128.6, 128.5 (2C), 128.2, 127.1, 127.0, 126.5, 126.4, 126.3, 125.1, 123.6, 123.0, 94.1, 88.5, 39.8, 35.0. HRMS (ED: calcd for C.sub.23H.sub.18 [M]+294.1409, found 294.1405. IR (neat, cm.sup.1): 3059, 3024, 1490, 1027.
Example 8. Scheme F: Procedure for Synthesis of Compound 1G
(185) ##STR00032##
(186) Allylation of Enynealcohol 1C (1G):
(187) To a suspension of NaH (60% dispersion in mineral oil) in THF (20 mL) was added cinnamyl alcohol 1C (0.5 g, 2.3 mmol) at room temperature. The mixture was stirred for 100 min at room temperature, after which allylbromide (7 mmol, 3 equiv) was added in one portion. The mixture was stirred for 1 h at room temperature, then filtered through a pad of silica gel. The solid was washed using hexane/ethyl acetate (1:1) as the eluent, and the filtrate was concentrated and purified by silica gel column chromatography, using 5% ethyl acetate in hexane as the eluent, to afford the title compound 1G (90% yield) as colorless oil.
Compound 1G: (E)-1-(3-(allyloxy)prop-1-en-1-yl)-2-(phenylethynyl)benzene
(188) ##STR00033##
(189) Chromatographic purification (5% ethyl acetate in hexane) afforded compound 1G (91% yield) as a white oil.; Rf=0.6 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.60-7.53 (4H, m), 7.39-7.35 (3H, m), 7.31 (1H, t, J=7.5 Hz), 7.26-7.22 (2H, m), 6.46-6.39 (1H, m), 6.03-5.93 (1H, m), 5.34 (1H, td, J=17.2, 1.2 Hz), 5.22 (1H, d, J=11.4 Hz), 4.24 (2H, d, J=6.0 Hz), 4.09 (2H, d, J=5.6 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.3, 134.9, 132.7, 131.7 (3C), 130.5, 128.6, 128.5 (2C), 128.2, 127.5, 125.3, 123.5, 122.1, 117.3, 94.2, 88.0, 71.3, 71.0. HRMS (EI): calcd for C.sub.20H.sub.18O [M]+274.1358, found 274.1354. IR (neat, cm.sup.1): 3059, 2849, 1492, 1069.
Example 9. Scheme G: AIBN/Bu3SnH Cyclization
(190) ##STR00034##
(191) The starting enyne (0.34 mmol) was degassed in 4 mL of toluene and heated to reflux. Two separate solutions of AIBN (0.5 eq.) and Bu.sub.3SnH (1.2 eq.) in 3 mL toluene were added using syringe pump through the top of a condenser over the course of 4 hours into the refluxing solution. The reaction was allowed to stir at reflux. After completion, confirmed by TLC, the solvent was evaporated and the product was dissolved in 20 mL DCM and washed with a 2M HCl solution to hydrolyze the tin. The product was purified on silica gel using a gradient of hexanes followed by ethyl acetate:hexane eluent.
Compound 3: 2-phenylnaphthalene
(192) ##STR00035##
(193) Chromatographic purification (hexane) afforded compound 3 as a white solid; m.p. 105-106 C.; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.06 (1H, s), 7.94-7.88 (3H, m), 7.78-7.74 (3H, m), 7.54-7.50 (4H, m), 7.40 (1H, t, J=7.3 Hz). .sup.13C NMR (150 MHz; CDCl.sub.3) 141.3, 38.8, 133.8, 132.8, 129.1 (2C), 128.6, 128.4, 127.8, 127.6 (2C), 127.5, 126.5, 126.1, 126.0, 125.8. HRMS (EI): calcd for C.sub.16H.sub.12 [M]+204.0939, found 204.0938. IR (neat, cm.sup.1): 3056, 2921, 1947, 1453.
Example 10. Procedure for the Synthesis of Compound M3
(194) ##STR00036##
(195) Allylation of Enyne Alcohol 1C (M3):
(196) To a suspension of NaH (60% dispersion in mineral oil) in THF (20 mL) was added enyne alcohol 1C (0.5 g, 2.3 mmol) at rt. The mixture was stirred for 100 min at rt, after which 2-(bromomethyl)naphthalene (1.0 equiv) was added in one portion. The mixture was stirred for 6 hours at room temperature, then filtrated through a pad of silica gel. The solid was washed using hexane/AcOEt (1/1) as the eluent, and the filtrate was concentrated and purified by silica gel column chromatography, using 10% Ethyl acetate in hexane as the eluent, to afford the title compound M3 (81% yield) as yellow oil.
Compound M3: (E)-2-(((3-(2-(phenylethynyl)phenyl)allyl)oxy)methyl)naphthalene
(197) ##STR00037##
(198) Chromatographic purification (10% ethyl acetate in hexane) afforded compound M3 (81% yield) as a yellow oil.; Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.89-7.83 (4H, m), 7.67-7.50 (7H, m), 7.39-7.29 (6H, m), 6.54 (1H, td, J=16.0, 5.8 Hz), 4.82 (2H, s), 4.37 (2H, dd, J=5.8, 1.1 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.3, 135.9, 133.5, 133.1, 132.7, 131.7 (2C), 130.5, 128.6, 128.5 (2C), 128.3, 128.2, 128.1, 127.8, 127.5, 126.6, 126.2, 126.0 (2C), 125.3, 123.4, 122.194.3, 88.0, 72.3, 70.9. HRMS (EI): calcd for C.sub.28H.sub.22O[M]+ 374.1671, found 374.1670.
2-((2-methoxyethoxy)methyl)-3-phenylnaphthalene (M6)
(199) ##STR00038##
(200) Chromatographic purification (5% ethyl acetate in hexane) afforded compound M6 (56% yield) as a pale-yellow oil. Rf=0.5 (5% ethyl acetate in hexane); 1H NMR (400 MHz; CDCl3) 8.03 (1H, s), 7.90-7.87 (1H, m), 7.84-7.80 (1H, m), 7.74 (1H, s), 7.50-7.44 (5H, m), 7.43-7.40 (1H, m), 4.60 (2H, s), 3.61-3.69 (2H, m), 3.57-3.54 (2H, m), 3.39 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 141.0, 140.1, 134.0, 132.9, 132.8, 129.6 (2C), 129.0, 128.3 (2C), 128.1, 128.0, 127.8, 127.4, 126.4, 126.2, 72.1, 72.6, 69.8, 59.2. HRMS (EI): calcd for C.sub.20H.sub.20O.sub.2[M]+292.1463, found 292.1459.
Example 11. Procedure for the Synthesis of Compound M5
(201) ##STR00039##
(202) Preparation of Wittig SaltBromo(2-bromobenzyl)triphenyl-.sup.5-Phosphane
(203) Bromobenzylbromide (2.49 g, 10.0 mmol) was added dropwise into a solution of triphenylphosphine (2.62 g, 10.0 mmol) in toluene in a pressure tube at room temperature. It was stirred for 8 h at 120 C. The separated solid was filtered through a Buchner funnel and the residue was washed with hexane. The resulting white solid was recrystallized from distilled petroleum ether (60-80 C.). Yield: 4.96 g, 97%.
(204) Wittig Reaction
(205) To a solution of the Wittig salt bromo(2-bromobenzyl)triphenyl-.sup.5-phosphane (3.6 g, 7 mmol) in anhydrous THF (10 mL) at 78 C. was added slowly n-BuLi (7 mL of a 1.0 M solution in hexane, 7.0 mmol). After 30 min, a solution of 1,4-dioxepan-6-one (0.812 g, 7.0 mmol) in THF (10 mL) was added dropwise. The resulting solution was stirred for 1 h at 78 C. and then at room temperature for 12 h and quenched with saturated NH.sub.4Cl solution. The aqueous phase was extracted with Et.sub.2O (330 mL), and the combined organic layers were washed with brine, dried over anhydrous Na.sub.2SO.sub.4, and evaporated under reduced pressure. The crude was purified by column chromatography (hexane) on silica gel affording 3 as colorless oil (1.18 g, 63%).
(206) Sonogashira Cross Coupling of Aryl Bromide 3 with Phenylacetylene (M5):
(207) A suspension of aryl bromide 3 (0.605 g, 2.25 mmol), PdCl.sub.2(PhCN).sub.2 (0.11 mmol), Cu(I) iodide (0.11 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.22 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of phenylacetylene (2.7 mmol) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds M5 (0.554 g, 85%) as brown oil.
Compound 3: 6-(2-bromobenzylidene)-1,4-dioxepane
(208) ##STR00040##
(209) Chromatographic purification (5% ethyl acetate in hexane) afforded compound 3 (63% yield) as a colorless oil. Rf=0.5 (5% ethyl acetate in hexane); 1H NMR (400 MHz; CDCl3) 7.56 (1H, dd, J=8.0, 0.6 Hz), 7.29-7.24 (2H, m), 7.13-7.08 (1H, m), 6.53 (1H, s), 4.44 (2H, d, J=0.4 Hz), 4.36 (2H, d, J=1.0 Hz), 3.77 (4H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 142.0, 136.3, 132.7, 130.6, 128.9, 127.7, 127.2, 123.8, 74.4, 73.9, 72.7, 72.0. HRMS (ED: calcd for C.sub.12H.sub.13BrO.sub.2 [M]+ 268.0099, found 268.0096.
Compound M5: 6-(2-(phenylethynyl)benzylidene)-1,4-dioxepane
(210) ##STR00041##
(211) Chromatographic purification (5% ethyl acetate in hexane) afforded compound M5 (85% yield) as a brown oil. Rf=0.5 (5% ethyl acetate in hexane); 1H NMR (400 MHz; CDCl3) 7.58-7.54 (3H, m), 7.39-7.34 (3H. m), 7.29-7.33 (2H, m), 7.28-7.24 (1H, m), 6.90 (1H, s), 4.52 (2H, d, J=1.3H), 4.51 (2H, s), 3.81 (4H, s).). .sup.13C NMR (100 MHz; CDCl.sub.3) 141.9, 138.1, 132.3, 1311.6 (2H, 128.9, 128.5 (2H), 128.2, 127.2, 127.0, 123.3, 122.7, 94.4, 88.1, 75.8, 74.0, 72.6, 70.4. HRMS (ED: calcd for C.sub.20H.sub.18O.sub.2[M]+ 290.1307, found 290.1302.
Example 12. General Procedure for the Synthesis of Enynes
(212) ##STR00042## ##STR00043## ##STR00044## ##STR00045##
(213) Sonogashira Cross Coupling of Aryl Bromide (4, 6) with TMS-Acetylene (5, 7):
(214) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2(PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.2 equiv. of acetylene (5.4 mmol) using a syringe. The reaction was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds 5 and 7 (92% and 84%) as brown oils.
(215) Removal of TMS (G1, G2):
(216) To a solution of enyne 5 and 7 (3.8 mmol) in MeOH-DCM (1:1, 10 mL), was added K.sub.2CO.sub.3 (0.54 mmol). The solution was stirred at room temperature for 2 h under argon. Water was added to quench the reaction and an aqueous work-up was performed. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compound G1 and G2 in 85% and 71% yield as yellow oils which were then used in subsequent Sonogashira reactions with Bromo and Iodo aryl compounds
(217) Sonogashira Cross Coupling of Aryl Bromides with Acetylenes G1 and G2 (K10, K14-K17):
(218) A suspension of aryl bromide (4.5 mmol), PdCl.sub.2(PhCN).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.45 mmol in a 10% solution of toluene) was added, immediately followed by 1.0 equiv. of acetylene (5.4 mmol) solution in dry THF using a syringe. The reaction was allowed to react for 12 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds K10, K14-K17.
(219) Sonogashira Cross Coupling of Aryl Iodide with Acetylenes G1 and G2 (K4-9, K13):
(220) A suspension of aryl iodide (3.5 mmol), PdCl.sub.2(PPh.sub.3).sub.2 (0.23 mmol), Cu(I) iodide (0.23 mmol) in 18 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame-dried round bottom flask. Then 1.0 equiv. of acetylene (3.5 mmol) solution in dry THF using a syringe. The reaction was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl iodide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride (230 mL), water (230 mL) and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed in vacuo. The reaction mixture was purified by flash chromatography on silica gel, (eluent: hexane/EtOAc) to afford compounds K4-9, K13.
Compound 5: (E)-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)trimethylsilane
(221) ##STR00046##
(222) Chromatographic purification (3% ethyl acetate in hexane) afforded compound 5 (92% yield) as a brown oil. Rf=0.5 (3% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.53 (1H, d, J=7.7 Hz), 7.45 (1H, dd, J=7.6, 1.0 Hz), 7.29-7.21 (1H, m), 7.17 (1H, dd, J=7.6, 1.1 Hz), 7.12 (1H, d, J=16.0 Hz), 6.35 (1H, td, J=16.0, 6.0 Hz), 4.13 (2H, dd, J=6.0, 1.5 Hz), 3.41 (3H, s), 0.28 (9H, s).). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.7, 132.9, 130.6, 128.8, 128.0, 127.4, 125.2, 122.0, 103.6, 99.4, 73.4, 58.1, 0.1 (3C). HRMS (EI): calcd for C.sub.15H.sub.20OSi [M]+224.1283, found 224.1281. IR (neat, cm.sup.1): 3039, 1488, 1070.
Compound G1: (E)-1-ethynyl-2-(3-methoxyprop-1-en-1-yl)benzene
(223) ##STR00047##
(224) Chromatographic purification (5% ethyl acetate in hexane) afforded compound G1 (85% yield) as a yellow oil. Rf=0.5 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.56 (1H, d, J=7.8 Hz), 7.49 (1H, dd, J=7.7, 1.1 Hz), 7.31 (1H, t, J=7.5 Hz), 7.19 (1H, dt, J=8.0, 0.9 Hz), 7.12 (1H, d, J=16.0 Hz), 6.36 (1H, td, J=16.0, 6.0 Hz), 4.13 (2H, dd, J=6.0, 1.4 Hz). 3.40 (3H, s), 3.33 (1H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.9, 133.3, 130.3, 129.1, 128.4, 127.4, 125.2, 120.9, 82.1 (2C), 73.3, 58.2. HRMS (ED: calcd for C.sub.12H.sub.12O [M]+172.0888, found 172.0884. IR (neat, cm.sup.1): 3299, 3020, 1497, 1011.
Compound G2: (E)-3-(2-ethynylphenyl)prop-2-en-1-ol
(225) ##STR00048##
(226) Chromatographic purification (15% ethyl acetate in hexane) afforded compound G2 (71% yield) as a yellow viscous oil. Rf=0.5 (5% ethyl acetate in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.51 (1H, d, J=7.9 Hz), 7.47 (1H, d, J=7.7 Hz), 7.27 (1H, t, J=7.6 Hz), 7.18 (1H, t, J=7.5 Hz), 7.10 (1H, d, J=16.0 Hz), 6.41 (1H, dt, J=16.0, 5.5 Hz), 4.33 (2H, d, J 5.5 Hz), 3.33 (1H, s), 2.56 (1H, bs). .sup.13C NMR (150 MHz; CDCl.sub.3) 138.8, 133.3, 131.0, 129.1, 128.6, 127.4, 125.1, 120.8, 82.2, 82.1, 63.7. HRMS (ED: calcd for C.sub.11H.sub.10O[M]+ 158.0732, found 158.0727.
Compound K4: (E)-3-(2-(p-tolylethynyl)phenyl)prop-2-en-1-ol
(227) ##STR00049##
(228) Chromatographic purification (15% ethyl acetate in hexane) afforded compound K4 (94% yield) as a brown liquid. Rf=0.6 (15% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.57-7.48 (4H, m), 7.28-7.16 (5H, m), 6.46 (1H, dt, J=16.0, 5.3 Hz), 4.39 (2H, d, J 5.3 Hz), 3.49 (1h, bs), 2.36 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.2, 137.8, 132.1, 131.1 (2C), 130.4, 128.9 (2C), 128.3, 128.0, 126.9, 124.8, 121.7, 119.6, 94.1, 87.0, 63.2, 21.2. HRMS (EI): calcd for C.sub.18H.sub.16O[M]+ 248.1201, found 248.1198. IR (neat, cm.sup.1): 3560 (b), 3022, 2978, 1444, 781.
Compound K5: (E)-1-((4-fluorophenyl)ethynyl)-2-(3-methoxyprop-1-en-1-yl)benzene
(229) ##STR00050##
(230) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K5 (86% yield) as a dark-brown oil. Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.60-7.52 (4H, m), 7.32-7.18 (3H, m), 7.10-7.04 (2H, m), 6.42 (1H, dt, J=16.0, 6.0 Hz), 4.17 (2H, dd, J=6.0, 1.52 Hz), 3.43 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 162.6 (d, J 248.3 Hz), 138.3, 133.5 (2C, d, J=8.3 Hz), 132.6, 130.3, 128.6, 128.2, 127.4, 125.3, 121.8, 119.5, 135.7 (2C, d, J=21.9 Hz), 93.1, 87.7, 73.3, 58.1. HRMS (ED: calcd for C.sub.18H.sub.15FO[M]+266.1107, found 266.1103. IR (neat, cm.sup.1): 3057, 2890, 1421, 790.
Compound K6: (E)-4-((2-(3-hydroxyprop-1-en-1-yl)phenyl)ethynyl)benzonitrile
(231) ##STR00051##
(232) Chromatographic purification (10% ethyl acetate in hexane) afforded compound K6 (92% yield) as a yellow solid. m. p. 157 C.; Rf=0.5 (15% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.61-7.60 (4H, m), 7.57 (1H, d, J=8.3 Hz), 7.52 (1H, dd, J=7.7, 1.1 Hz), 7.33 (1H, dt, J=7.59, 1.2 Hz), 7.24 (1H, dt, J=7.6, 1.2 Hz), 7.13 (1H, d, J=16.0 Hz), 7.47 (1H, dt, J=16.0, 5.5 Hz), 4.38 (2H, dd, J=5.5, 1.6 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.4, 132.7, 132.0 (2C), 131.9 (2C), 131.1, 129.3, 128.2, 128.1, 127.4, 125.2, 120.7, 118.4, 111.4, 92.2, 92.1, 63.6. HRMS (ED: calcd for C.sub.18H.sub.13NO[M]+ 259.0997, found 259.0992. IR (neat, cm.sup.1): 3566 (b), 3095, 2709, 2276, 1482.
Compound K7: (E)-1-(4-((2-(3-hydroxyprop-1-en-1-yl)phenyl)ethynyl)phenyl)ethan-1-one
(233) ##STR00052##
(234) Chromatographic purification (10% ethyl acetate in hexane) afforded compound K7 (82% yield) as a brown oil. Rf=0.4 (15% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.93 (2H, d, J=8.4 Hz), 7.61 (2H, d, J=8.0 Hz), 7.57 (1H, d, J=7.7 Hz), 7.53 (1H, d, J=7.7 Hz), 7.33 (1H, t, 7.5 Hz), 7.24 (1H, t, J=7.6 Hz), 7.17 (1H, d, J=16.0 Hz), 6.48 (1H, dt, J=16.0, 5.6 Hz), 4.39 (2H, d, J=5.6 Hz), 2.60 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 197.6, 138.5, 132.8, 131.7 (2C), 131.2, 129.2, 128.5, 128.4 (2C), 128.3, 127.5, 125.3, 121.3, 93.3, 91.3, 63.8, 26.7.23 HRMS (EI): calcd for C.sub.19H.sub.16O.sub.2[M]+ 276.1150, found 276.1148. IR (neat, cm.sup.1): 3456 (b), 3091, 2813, 1756.
Compound K8: (E)-1-((4-methoxyphenyl)ethynyl)-2-(3-methoxyprop-1-en-1-yl)benzene
(235) ##STR00053##
(236) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K8 (90% yield) as a yellow semisolid. Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.57 (1H, dd, J=7.9, 1.3 Hz), 7.51-7.45 (3H, m), 7.29 (1H, dd, J=7.6, 1.5 Hz), 7.23-7.16 (2H, m), 6.91-6.87 (2H. m), 6.39 (1H, dt, J=16.0 Hz), 4.16 (2H, dd, J=5.6, 1.5 Hz). 3.84 (3H, s), 3.41 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 159.9, 138.1, 133.2 (2C), 132.6, 130.9, 128.3, 127.9, 127.5, 125.4, 115.7, 114.3 (2C), 94.3, 86.7, 73.5, 58.2, 55.5. HRMS (EI): calcd for C.sub.19H.sub.18O.sub.2 [M]+ 278.1307, found 278.1305. IR (neat, cm.sup.1): 3075, 2998, 1523, 976.
Compound K9: (E)-3-(2-(thiophen-2-ylethynyl)phenyl)prop-2-en-1-ol
(237) ##STR00054##
(238) Chromatographic purification (20% ethyl acetate in hexane) afforded compound K9 (91% yield) as a yellow oil. Rf=0.5 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.55 (1H, d, J=7.7 Hz), 7.50 (1H, d, J=7.6 Hz), 7.31-7.7.27 (3H, m), 7.26-7.21 (1H, m), 7.12 (1H, d, J=15.8 Hz), 7.03-7.01 (1H, m), 6.46 (1H, dt, J=15.8, 5.6 Hz), 4.37 (2H, d, J=5.6 Hz), 1.97 (1H, bs). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.1, 132.5, 132.0, 130.9, 128.9, 128.8, 127.6, 127.5, 127.3, 125.3, 123.3, 121.6, 91.7, 87.4, 63.9. HRMS (ED: calcd for C.sub.15H.sub.12OS[M]+240.0609, found 246.0605 IR (neat, cm.sup.1): 3610 (b), 3075, 2811, 1498, 978.
Compound K10: (E)-2-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)pyridine
(239) ##STR00055##
(240) Chromatographic purification (10% ethyl acetate in hexane) afforded compound K10 (77% yield) as a yellow oil. Rf=0.5 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.60 (1H, d, J=4.3 Hz), 7.65 (1H, dt, J=7.6, 1.8 Hz), 7.56 (2H, d, J=7.9 Hz), 7.51 (1H, d, J=7.8 Hz), 7.30 (1H, t, J=7.1 Hz), 7.23-7.16 (3H, m), 6.38 (1H, dt, J=16.0, 6.0 Hz), 4.13 (2H, dd, J=6.0, 1.4 Hz), 3.38 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 150.2, 143.6, 138.8, 136.3, 133.2, 130.2, 129.3, 128.5, 127.5, 127.4, 125.3, 122.9, 121.0, 93.3, 87.7, 73.3, 58.1. HRMS (ED: calcd for C.sub.17H.sub.15NO[M]+ 249.1154, found 249.1150. IR (neat, cm.sup.1): 3029, 2878, 1533, 988.
Compound K11: (E)-3-(2-(pyrimidin-5-ylethynyl)phenyl)prop-2-en-1-ol
(241) ##STR00056##
(242) Chromatographic purification (20% ethyl acetate in hexane) afforded compound K11 (85% yield) as a brown solid. m. p. 163 C.; Rf=0.5 (25% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 9.11 (1H, s), 8.84 (2H, s), 7.58 (1H, d, J=8.0 Hz), 7.54-7.50 (1H, m), 7.35 (1H, t, J=7.4 Hz), 7.24 (1H, dt, J=7.6, 1.0 Hz), 7.12 (1H, d, J=15.9 Hz), 6.48 (1H, dt, J=15.9, 5.4 Hz), 4.39 (2H, dd, J=5.4, 1.5 Hz), 2.42 (1H, bs). .sup.13C NMR (100 MHz; CDCl.sub.3) 158.7 (2C), 156.8, 154.4, 138.8, 132.9, 131.8, 129.8, 128.1, 127.6, 125.5, 120.4, 95.1, 86.9, 63.3. HRMS (ED: calcd for C.sub.15H.sub.12N.sub.2O[M]+ 236.0950, found 236.0944. IR (neat, cm.sup.1): 3560 (b), 3075, 2811, 1498, 978.
Compound K13: (E)-3-(2-(o-tolylethynyl)phenyl)prop-2-en-1-ol
(243) ##STR00057##
(244) Chromatographic purification (15% ethyl acetate in hexane) afforded compound K13 (89% yield) as a brown oil. Rf=0.6 (15% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.57 (1H, d, J=7.9 Hz), 7.53 (1H, t, J=7.0 Hz), 7.29 (1H, t, J=7.5 Hz), 7.26-7.22 (5H, m), 7.20-7.18 (1H, m), 6.46 (1H, dt, J=16.0, 5.4 Hz), 4.36 (2H, d, J=5.4 Hz), 2.54 (3H, s), 2.21 (1H, bs). .sup.13C NMR (100 MHz; CDCl.sub.3) 162.6 (d, J=248.3 Hz), 140.2, 138.2, 132.7, 132.0, 130.8, 129.7, 129.2, 128.6 (2C), 127.5, 125.8, 15.2, 123.2, 122.4, 93.3, 91.9, 63.9, 21.12. HRMS (ED: calcd for C.sub.18H.sub.16O[M]+ 248.1201, found 248.1200. IR (neat, cm.sup.1): 3029, 2993, 1439, 778.
Compound K14: (E)-2-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)-1,1-biphenyl
(245) ##STR00058##
(246) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K14 (92% yield) as a yellow oil. Rf=0.5 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.71-7.67 (2H, m), 7.54 (1H, d, J=7.5 Hz), 7.47-7.35 (9H, m), 7.26 (1H, t, J=6.2 Hz), 7.19 (1H, dt, J=7.6, 0.9 Hz), 6.86 (1H, d, J=16.0 Hz), 6.30 (1H, dt, J=16.0, 6.2 Hz), 4.00 (2H, dd, J=6.2, 1.2 Hz), 3.38 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 143.9, 140.8, 138.1, 134.0, 133.8, 133.3, 132.7, 130.8, 129.8, 129.5 (2C), 128.8, 128.5, 128.2 (2C), 127.9, 127.7, 127.4, 127.3, 125.1, 122.3, 121.9, 94.00, 90.8, 73.3, 58.0, HRMS (EI): calcd for C.sub.24H.sub.20O [M]+324.1514, found 324.1511. IR (neat, cm.sup.1): 3288, 3033, 1452, 998.
Compound 15: (E)-2-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)naphthalene
(247) ##STR00059##
(248) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K15 (89% yield) as a yellow semisolid. Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.09 (1H, s), 7.86-7.83 (3H, m), 7.63-7.58 (3H, m), 7.53-7.50 (2H, m), 7.35-7.24 (3H, m), 6.44 (1H, dd, J=16.0, 6.0 Hz), 4.20 (2H, dd, J=6.0, 1.3 Hz), 3.46 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.4, 133.2, 133.0, 132.8, 131.5, 130.6, 128.7, 128.5, 128.2, 128.1, 128.0 (2C), 127.6, 126.9, 126.8, 125.4, 122.1, 120.8, 94.7, 88.4, 73.5, 58.2. HRMS (EI): calcd for C.sub.22H.sub.18O [M]+ 298.1358, found 298.1355. IR (neat, cm.sup.1): 3055, 2921, 1446, 1112.
Compound K16: (E)-1-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)naphthalene
(249) ##STR00060##
(250) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K16 (73% yield) as a yellow semisolid. Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.51 (1H, d, J=8.1 Hz), 7.88 (2H, t, J=9.0 Hz), 7.81 (1H, dd, J=7.1, 1.0 Hz), 7.68-7.61 (3H, m), 7.58-7.54 (1H, s), 7.49 (1H, dd, J=7.3, 0.9 Hz), 7.37-7.34 (2H, m), 7.30 (1H, dt, J=7.5, 1.3 Hz), 6.46 (1H, td, J=16.0, 6.0 Hz), 4.20 (2H, dd, J=6.0, 1.5 Hz). 3.45 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.4, 133.4, 132.8, 130.7, 130.6, 129.0, 128.8, 128.5 (2C), 128.3, 127.6, 127.0, 126.6, 126.4, 125.5, 12504, 122.3, 121.2, 92.9, 92.4, 73.4, 58.2. HRMS (ED: calcd for C.sub.22H.sub.18O [M]+ 298.1358, found 298.1356. IR (neat, cm.sup.1): 3059, 2903, 1456, 1009.
Compound K17: (E)-9-((2-(3-methoxyprop-1-en-1-yl)phenyl)ethynyl)anthracene
(251) ##STR00061##
(252) Chromatographic purification (5% ethyl acetate in hexane) afforded compound K17 (62% yield) as a yellow semisolid. Rf=0.6 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.70 (2H, d, J=8.5 Hz), 8.44 (1H, s), 8.03 (2H, d, J=8.5 Hz), 7.80-7.78 (1H, m), 7.67 (1H, d, J=8 Hz), 7.61 (2H, dt, J=6.6, 1.0 Hz), 7.57-7.51 (3H, m), 7.41-7.32 (2H, m), 6.48 (1H, dt, J=15.9, 5.9 Hz), 4.23 (2H, dd, J=5.9, 1.3 Hz), 3.46 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.5, 132.8, 131.4, 130.9, 128.9, 128.5, 128.0, 127.7, 127.0, 126.8, 125.9, 125.5, 122.6, 117.6, 99.4, 91.3, 73.4, 58.3. HRMS (ED: calcd for C.sub.26H.sub.20O [M]+ 348.1514, found 348.11511. IR (neat, cm.sup.1): 3088, 2828, 1466, 998.
Example 13. Procedure for the Synthesis of Compound K12
(253) ##STR00062##
(254) Wittig Reaction (8):
(255) Ethyl (triphenylphosphoranylidene) acetate (2.80 g, 8.17 mmol) was added to a solution of 2-bromonicotinaldehyde (1.0 g, 5.4 mmol) in dry DCM (dichloromethane) at 0 C. and stirred for 8 h at room temperature. The solvent was then evaporated under vacuum. The colorless oil was partitioned between ethylacetate and water. The organic layer was washed with water, brine and dried over Na.sub.2SO.sub.4. It was then filtered and evaporated to give an oil from which the title compound 8 was isolated by column chromatography (Si-gel, PE:EA=15:1). Yield: 1.3 g, 94%; State: colorless oil.
(256) DIBAL-H Reduction of ,-Unsaturated Ester 8 (9):
(257) A THF solution of compound 8 (1.3 g, 5.2 mmol) was cooled to 0 C. Diisobutylaluminum hydride (DIBAL-H, 1.0 M in hexane, 14 mL, 14 mmol) was slowly added to this solution under a nitrogen atmosphere and was stirred for 6 h. The reaction was quenched with aq. NH.sub.4Cl sol. (20 mL) and extracted with ethyl acetate (100 mL). The extract was washed with brine solution, dried over MgSO.sub.4, and concentrated under reduced pressure. The residue was eluted through a silica column to afford 9 as a colorless oil (0.930 g, 84%).
(258) Sonogashira Cross Coupling of Aryl Bromides 9 with 2-ethynylpyridine (K12):
(259) A suspension of aryl bromide 9 (0.480 g, 2.25 mmol), PdCl.sub.2(PhCN).sub.2 (0.11 mmol), Cu(I) iodide (0.11 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.23 mmol in a 10% solution of toluene) was added, immediately followed by 1.0 equiv. of 2-ethynylpyridine (2.25 mmol) using a syringe. The reaction was allowed to react for 12 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compound K12 (0.510 g, 96%) as brown oil.
Compound 8: ethyl (E)-3-(2-bromopyridin-3-yl)acrylate
(260) ##STR00063##
(261) Chromatographic purification (10% ethyl acetate in hexane) afforded compound 8 (94% yield) as a colorless oil. Rf=0.7 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.32 (1H, dd, J=4.68, 1.9 Hz), 7.89 (1H, d, J=16.0 Hz), 7.84 (1H, dd, J=7.7, 1.9 Hz), 7.30-7.28 (1H, m), 6.38 (1H, d, J=16.0 Hz), 4.25 (2H, q, J=7.1 Hz), 1.31 (3H, t, J=7.1 Hz). HRMS (EI): calcd for C.sub.10H.sub.10BrNO.sub.2[M]+ 258.9895, found 254.9892.
Compound 9: (E)-3-(2-bromopyridin-3-yl)prop-2-en-1-ol
(262) ##STR00064##
(263) Chromatographic purification (20% ethyl acetate in hexane) afforded compound 9 (84% yield) as a colorless oil. Rf=0.3 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.11-8.09 (1H, m), 7.67 (1H, d, J=7.7 Hz), 7.14-7.12 (1H, m), 6.76 (1H, d, J=15.9 Hz), 6.26 (1H, dt, J=15.9, 5.1 Hz), 4.30 (2H, d, J=5.1 Hz), 3.69 (1H, bs). .sup.13C NMR (100 MHz; CDCl.sub.3) 148.4, 142.7, 138.7, 135.1, 134.4, 126.8, 123.2, 62.8. HRMS (EI): calcd for C.sub.8H.sub.8BrNO[M]+ 212.9789, found 212.9787.
Compound K12: (E)-3-(2-(pyridin-2-ylethynyl)pyridin-3-yl)prop-2-en-1-ol
(264) ##STR00065##
(265) Chromatographic purification (20% ethyl acetate in hexane) afforded compound K12 (96% yield) as a Brown oil. Rf=0.3 (20% ethyl acetate in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.52 (1H, d, J=7.0 Hz), 8.39 (1H, dd, J=4.5.0, 1.3 Hz), 7.74-7.73 (1H, m), 7.63-7.60 (1H, m), 7.54 (1H, d, J=7.8 Hz), 7.21-7.18 (1H, m), 7.15-7.13 (1H, m), 7.12 (1H, d, J=16.0 Hz), 6.46 (1H, dt, J=16.0, 5.0 Hz), 4.35 (2H, dd, J=5.0, 1.5 Hz). .sup.13C NMR (150 MHz; CDCl.sub.3) 149.9, 148.6, 142.4, 140.2, 136.6, 135.7, 135.1, 132.7, 128.0, 125.0, 123.7, 123.6, 91.7, 86.9, 62.8. HRMS (ED: calcd for C.sub.15H.sub.12N.sub.2O[M]+ 236.0950, found 236.0944.
Example 14. Procedure for the Synthesis of Compound L1
(266) ##STR00066##
(267) Sonogashira Cross Coupling of Aryl Bromides G1 with Hex-1-yne:
(268) A suspension of aryl bromide G1 (0.511 g, 2.25 mmol), PdCl.sub.2(PhCN).sub.2 (0.11 mmol), Cu(I) iodide (0.11 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.23 mmol in a 10% solution of toluene) was added, immediately followed by 1.0 equiv. of hex-1-yne (2.25 mmol) using a syringe. The reaction was allowed to react for 12 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compound L1 (0.451 g, 88%) as brown liquid.
Compound L1: (E)-1-(hex-1-yn-1-yl)-2-(3-methoxyprop-1-en-1-yl)benzene
(269) ##STR00067##
(270) Chromatographic purification (5% ethyl acetate in hexane) afforded compound L1 (88% yield) as a brown liquid. Rf=0.5 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.52 (1H, d, J=7.6 Hz), 7.40-7.37 (1H, m), 7.22 (1H, t, J=7.1 Hz), 7.18-7.15 (1H, m), 7.12 (1H, d, J=16.2 Hz), 6.33 (1H, dt, J=16.2, 6.1 Hz), 4.13 (2H, dd, J=6.1, 1.3 Hz), 3.40 (3H, s), 2.48 (2H, t, J=6.9 Hz), 1.65-1.48 (4H, m), 1.0 (3H, t, J=7.2 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.1, 132.7, 131.1, 127.8, 127.4 (2C), 125.1, 123.0, 95.5, 79.1, 73.5, 58.1, 31.0, 22.2, 19.5, 13.8. HRMS (EI): calcd for C.sub.16H.sub.20O[M]+ 228.1514, found 228.1511. IR (neat, cm.sup.1): 3022, 2978, 1444, 781.
Example 15. General Procedures for the Synthesis of Compounds L4, L4, P7
(271) ##STR00068##
(272) Wittig Reaction (11):
(273) Ethyl (triphenylphosphoranylidene) acetate (1.5 eq. for each aldehyde group) was added to a solution of bromoaldehyde in dry DCM (dichloromethane) at 0 C. and stirred for 8 h at room temperature. The solvent was then evaporated under vacuum. The colorless oil was partitioned between ethylacetate and water. The organic layer was washed with water, brine and dried over Na.sub.2SO.sub.4. It was then filtered and evaporated to give an oil from which the title compound 11 was isolated by column chromatography (Si-gel, PE:EA=15:1). State: colorless viscous oil.
(274) DIBAL-H Reduction of ,-Unsaturated Ester 11 and 14 (12 and 15):
(275) A THF solution of bromo ester compound (11 and 14) was cooled to 0 C. Diisobutylaluminum hydride (DIBAL-H, 1.0 M in hexane, 1 eq. for each ester group) was slowly added to this solution under a nitrogen atmosphere and was stirred for 6 h. The reaction was quenched with aq. NH.sub.4Cl sol. (20 ml) and extracted with ethyl acetate (100 ml). The extract was washed with brine solution, dried over MgSO.sub.4, and concentrated under reduced pressure. The residue was directly used for the next step without further purification.
(276) Methylation of Bromocinnamyl Alcohol (12 and 15):
(277) To a suspension of NaH (60% dispersion in mineral oil; 1.5 eq. for each alcohol group) in THF (20 mL) was added bromocinnamyl alcohol (Crude from the previous step) at room temperature. The mixture was stirred for 100 min at room temperature, after which MeI (3 eq. for each alcohol group) was added in one portion. The mixture was stirred for 6 h at room temperature, then filtrated through a pad of silica gel. The solid was washed using hexane/ethyl acetate (1:1) as the eluent, and the filtrate was concentrated and purified by silica gel column chromatography, using 10% ethylacetate in hexane as the eluent, to afford the title compound 12 and 15 (95% and 91% yield) as colorless oil.
(278) Sonogashira Cross Coupling of Aryl Bromides (11, 12, 15) with Phenylacetylene (L4, L4, P7):
(279) A suspension of aryl bromide (2.2 mmol), PdCl.sub.2(PhCN).sub.2 (0.22 mmol for 11 and 12 and 0.33 mmol for 15), Cu(I) iodide (0.22 mmol for 11 and 12 and 0.33 mmol for 15) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.44 mmol for 11 and 12 and 0.66 mmol for 15 in a 1 M solution of toluene) was added, immediately followed by phenylacetylene (5.3 mmol for 11 and 12 and 7.9 mmol for 15) using a syringe. The mixture was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with DCM (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixtures were purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds L4, L4 and, P7 in 77%, 86% and, 73% yields respectively.
Compound 11: diethyl 3,3-(2,5-dibromo-1,4-phenylene)(2E,2E)-diacrylate
(280) ##STR00069##
(281) Chromatographic purification (10% ethyl acetate in hexane) afforded compound 11 (82% yield) as a gummy oil. Rf=0.3 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.91 (2H, d, H=15.9 Hz), 7.82 (2H, s), 6.42 (2H, d, J=15.9 Hz), 4.28 (4H, q, J=7.1 Hz), 1.34 (6H, t, J=7.1 Hz).
Compound L3: 1-((Z)-hex-1-en-1-yl)-2-((E)-3-methoxyprop-1-en-1-yl)benzene
(282) ##STR00070##
(283) Chromatographic purification (5% ethyl acetate in hexane) afforded compound L3 (70% yield) as a yellow oil. Rf=0.5 (5% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.52-7.5 (1H, m), 7.24-7.16 (3H, m), 6.79 (1H, d, J=15.9 Hz), 6.50 (1H, d, J=11.4 Hz), 6.21 (1H, dt, J=15.9, 6.0 Hz), 5.76 (1H, dt, J=11.4, 7.4 Hz), 4.10 (2H, dd, J=6.1, 1.3 Hz), 3.39 (3H, s), 2.13-2.08 (1H, m), 1.40-1.27 (4H, m), 0.85 (3H, t, J=7.2 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 136.4, 135.4, 134.1, 131.1, 129.8, 127.7, 127.3, 127.2, 127.1, 125.9, 73.6, 58.1, 32.0, 28.35, 22.5, 14.1. HRMS (EI): calcd for C.sub.16H.sub.22O[M]+ 230.1671, found 230.1666.23.
Compound L4: diethyl 3,3-(2,5-bis(phenylethynyl)-1,4-phenylene)(2E,2E)-diacrylate
(284) ##STR00071##
(285) Chromatographic purification (10% ethyl acetate in hexane) afforded compound L4 (63% yield) as a brown semisolid. Rf=0.3 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.22 (2H, d, J=15.9 Hz), 7.85 (1H, s), 7.61-7.59 (4H, m), 7.40-7.38 (6H, m), 6.65 (2H, d, J=15.9 Hz), 4.29 (4H, q, J=7.1 Hz), 1.36 (6H, t, J=7.1 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 166.5 (2C), 140.9 (2C), 136.6 (2C), 131.7 (4C), 130.5 (2C), 129.0 (2C), 128.5 (4C), 123.9 (2C), 122.4 (2C), 121.3 (2C), 97.3 (2C), 86.4 (2C), 60.7 (2C), 14.3 (2C). HRMS (ED: calcd for C.sub.32H.sub.26O.sub.4[M]+ 474.1831, found 474.1828. IR (neat, cm.sup.1): 3029, 1745.
Compound L5: diethyl 2,2-(2,6-diphenyl-1,5-dihydro-s-indacene-1,5-diyl)diacetate
(286) ##STR00072##
(287) Chromatographic purification (10% ethyl acetate in hexane) afforded compound L5 (20% yield) as a yellow solid. m. p. 93-94 C. Rf=0.3 (20% ethyl acetate in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.30 (4H, d, J=7.0 Hz), 7.49 (2H, s), 7.29 (2H, t, J=7.0 Hz), 7.11 (2H, s), 4.42 (2H, d, J=8.2 Hz), 4.26-4.15 (4H, m), 2.93 (2H, d, J=16.2 Hz), 2.22-2.16 (2H, m), 1.25 (6H, t, J=7.0 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 172.9 (2C), 150.2 (2C), 147.4 (2C), 143.9 (2C), 135.0 (2C), 129.0 (4C), 127.8 (2C), 127.1 (4C), 125.3 (2C), 121.1 (2C), 60.8 (2C), 45.6 (2C), 37.0 (2C), 14.4 (2C). (HRMS (ED: calcd for C.sub.32H.sub.30O.sub.4[M]+ 478.2144, found 478.2142.
Compound 12: 1,4-dibromo-2,5-bis((E)-3-methoxyprop-1-en-1-yl)benzene
(288) ##STR00073##
(289) Chromatographic purification (10% ethyl acetate in hexane) afforded compound 12 as a yellow viscous oil. Rf=0.3 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.67 (2H, s), 6.82 (2H, d, J=15.8 Hz), 6.22 (2H, dt, J=15.8, 5.4 Hz), 4.10 (4H, dd, J=5.4, 1.4 Hz), 3.39 (6H, s). .sup.13C NMR (150 MHz; CDCl.sub.3) 137.3 (2C), 131.0 (2C), 130.4 (2C), 129.4 (2C), 122.6 (2C), 72.8 (2C), 58.4 (2C).
Compound L4: ((2,5-bis((E)-3-methoxyprop-1-en-1-yl)-1,4-phenylene)bis(ethyne-2,1-diyl))dibenzene
(290) ##STR00074##
(291) Chromatographic purification (10% ethyl acetate in hexane) afforded compound L4 (86% yield) as a yellow semisolid. Rf=0.3 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.75 (2H, s), 7.58-7.57 (4H, m), 7.42-7.38 (6H, m), 7.14 (2H, d, J=16.0 Hz), 6.45 (2H, dt, J=16.0, 5.4 Hz), 4.17 (4H, d, J=5.4 Hz), 3.43 (6H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 137.2 (2C), 131.7 (4C), 129.4 (4C), 128.8 (2C), 128.6 (4C), 123.2 (2C), 122.1 (2C), 95.5 (2C), 87.7 (2C), 73.3 (2C), 58.2 (2C). HRMS (EI): calcd for C.sub.30H.sub.22O.sub.2[M]+ 418.1933, found 418.1930.
Compound 14: triethyl 3,3,3-(2,4,6-tribromobenzene-1,3,5-triyl)-triacrylate
(292) ##STR00075##
(293) Chromatographic purification (10% ethyl acetate in hexane) afforded compound 14 (80% yield) as a pale-yellow semisolid. Rf=0.3 (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.43 (2H, d, J=16.3 Hz), 6.10 (2H, d, J=16.3 Hz), 4.18 (4H, q, J=7.1 Hz), 1.25 (6H, t, J=7.1 Hz,).
Compound P7: ((2,4,6-tris((E)-3-methoxyprop-1-en-1-yl)benzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tribenzene
(294) ##STR00076##
(295) Chromatographic purification (10% ethyl acetate in hexane) afforded compound P7 (73% yield) as a brown solid. Rf=0.3 m. p. 133 C. (10% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.54 (6H, dd, J=6.4, 3.0 Hz), 7.42-7.34 (9H, m), 7.16 (3H, d, J=16.1 Hz), 6.85 (3H, dt, J=16.1, 5.8 Hz), 4.31-4.16 (6H, m), 3.45 (9H, s). .sup.13C NMR (100 MHz, CDCl.sub.3) 141.1 (3C), 133.7 (3C), 131.5 (6C), 129.6 (3C), 128.7 (3C), 128.6 (6C), 123.5 (3C), 119.6 (3C), 99.2 (3C), 87.8 (3C), 73.6 (3C), 58.0 (3C). HRMS (ED: calcd for C.sub.42H.sub.36O.sub.3[M]+ 588.2664, found 588.2661.
Example 16. General Procedures Bu3SnH/AIBN Radical Reaction
(296) ##STR00077##
(297) The starting enyne (K1-17) (0.34 mmol) was degassed in 4 mL of toluene and heated to reflux. Two separate solutions of AIBN (0.5 equiv.) and Bu.sub.3SnH (1.2 equiv.) each in 3 mL toluene were added using syringe pump through the top of a condenser over the course of 4 hours into the refluxing solution. The reaction was stirred at reflux for 12 h. After completion, confirmed by TLC, the solvent was evaporated and the product was dissolved in 20 mL DCM and washed with a 2 M HCl solution to accomplish protodestannylation. The products were purified on silica gel using a gradient of hexanes followed by ethyl acetate:hexane eluent.
Example 17. General Procedure for Stille Coupling
(298) ##STR00078##
(299) A solution of enyne (0.34 mmol) in toluene was brought to reflux. A solution of tributyltin hydride (1.2 equiv.) and AIBN (0.5 equiv.) in toluene was added dropwise to the refluxing solution. The reaction mixture was allowed to reflux for 12 hours. Toluene was evaporated in vacuum. A two-neck flask was charged with lithium bromide (2.04 mmol) and flame dried under high vacuum. Upon cooling, tetrakis(triphenylphosphine) palladium(0) (0.034 mmol), CuCl (1.7 mmol) were added, and the mixture was degassed (4) under high vacuum with an argon purge. Dry DMF (4.0 mL) was introduced with concomitant stirring, followed by the addition of aryl iodide (0.35 mmol) and the tributyltin reaction mixture. The resulting mixture was rigorously degassed (4) by the freeze-pump-thaw method using liquid nitrogen under argon atmosphere. The reaction mixture was stirred at room temperature for 1 h, then heated to 110 C. for 12 hours. Following completion of the coupling as monitored by TLC, the reaction mixture was cooled, diluted with Et.sub.2O, and washed with brine. The aqueous layer was further extracted with Et.sub.2O (3), the combined organic layers were washed with water (240 mL) and brine (240 mL), and dried over Na.sub.2SO4. Concentration in vacuum afforded a residue that was purified by column chromatography (Si-gel/10% ethyl acetate in hexane) to afford O4 and O2 (52% and 63%) as a yellow and white solid.
Compound O2: 2-phenyl-1,1-binaphthalene
(300) ##STR00079##
(301) Chromatographic purification (hexane) afforded compound 02 (63% yield) as a white solid; m.p. 133 C.; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.05 (1H, d, J=8.5 Hz), 7.99 (1H, d, J=8.2 Hz), 7.89 (1H, d, J=8.2 Hz), 7.83 (1H, d, J=8.2 Hz), 7.70 (1H, d, H=8.5 Hz), 7.52-7.40 (4H, m), 7.31-7.27 (4H, m), 7.14-7.11 (2H, m), 7.07-7.03 (3H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 142.1, 139.7, 137.1, 135.9, 133.7, 133.5, 133.4, 132.8, 129.4 (2C), 128.6, 128.4, 128.2, 128.1, 127.9, 128.7, 127.6, 127.4, 126.8, 126.5, 126.2, 125.9, 125.8, 125.4. HRMS (ED: calcd for C.sub.26H.sub.18[M]+ 330.1409, found 330.1405.
Example 18. General Procedures for the Synthesis of Compounds P3 & P5
(302) ##STR00080##
(303) Sonogashira Cross Coupling of 1,4-Dibromobenzene and 1,3-Dibromobenzene with Acetylene G2 (P3 and P5):
(304) A suspension of dibromobenzene (2 mmol), PdCl.sub.2(PhCN).sub.2 (0.20 mmol), Cu(I) iodide (0.20 mmol) in 20 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame dried round bottom flask. Once the reaction mixture was completely thawed and the atmosphere replaced with argon, tri-tert-butylphosphine (0.40 mmol in a 10% solution of toluene) was added, immediately followed by 2.0 equiv. of acetylene G1 (4.0 mmol) solution in dry THF using a syringe. The reaction was allowed to react for 12 hours and monitored by TLC. After total consumption of the aryl bromide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride, water and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed under reduced pressure. The reaction mixture was purified by flash chromatography (eluent: hexane/ethyl acetate) on silica gel to afford compounds P5 (90%) and P3 (88%) as oils.
Compound P5: 1,4-bis((2-((E)-3-methoxyprop-1-en-1-yl)phenyl)ethynyl)benzene
(305) ##STR00081##
(306) Chromatographic purification (15% ethyl acetate in hexane) afforded compound P5 (90% yield) as a dark brown oil. Rf=0.6 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.59-7.57 (2H, m), 7.55 (4H, s), 7.53-7.52 (2H, m), 7.31 (2H, dt, J=7.4, 1.1 Hz), 7.23 (2H, dt, J=7.6, 1.2 Hz), 7.20 (2H, d, J=16.0 Hz), 6.41 (2H, td, J=16.0, 6.0 Hz), 4.17 (4H, dd, J=6.0, 1.4 Hz), 3.43 (6H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 138.3 (2C), 132.6 (2C), 131.5 (4C), 130.2 (2C), 128.8 (2C), 128.2 (2C), 127.4 (2C), 125.2 (2C), 123.3 (2C), 121.7 (2C), 93.8 (2C), 89.9 (2C), 73.2 (2C), 58.1 (2C). HRMS (ED: calcd for C.sub.30H.sub.26O.sub.2 [M]+ 418.1933, found 418.1926. IR (neat, cm.sup.1): 3059, 2221, 1498, 966.
Compound P3: 1,3-bis((2-((E)-3-methoxyprop-1-en-1-yl)phenyl)ethynyl)benzene
(307) ##STR00082##
(308) Chromatographic purification (15% ethyl acetate in hexane) afforded compound P3 (88% yield) as a light brown oil. Rf=0.6 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.75 (1H, t, J=1.5 Hz), 7.59 (2H, d, J=7.7 Hz), 7.55-7.52 (4H, m), 7.37 (1H, t, J 7.9 Hz), 7.32 (2H, dt, J=7.4, 1.1 Hz), 7.24 (2H, m), 7.20 (2H, d, J=16.0 Hz), 6.41 (2H, td, J=16.0, 6.0 Hz), 4.17 (4H, dd, J=6.0, 1.4 Hz), 3.43 (6H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) (2C), 134.5, 132.8 (2C), 131.5 (2C), 130.4 (2C), 128.9, 128.7 (2C), 128.3 (2C), 127.5 (2C), 125.3 (2C), 123.9 (2C), 121.8 (2C), 93.3 (2C), 88.6 (2C), 73.4 (2C), 58.2 (2C). HRMS (EI): calcd for C.sub.30H.sub.26O.sub.2 [M]+ 418.1933, found 418.1929. IR (neat, cm.sup.1): 3051, 2224, 1488, 978.
Compound P4: 1,3-di(naphthalen-2-yl)benzene
(309) ##STR00083##
(310) Chromatographic purification (40% DCM in hexane) afforded compound P4 (65% yield) as a white solid; m.p. 142-143 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.15 (2H, s), 8.08 (1H, t, J=1.7 Hz), 7.97 (2H, d, J=8.6 Hz), 7.95 (2H, d, J=7.7 Hz), 7.91 (2H, d, J=7.7 Hz), 7.86 (2H, dd, J=8.5, 1.8 Hz), 7.76 (2H, dd, J=7.6, 1.8 Hz), 7.62 (1H, t, J=7.6 Hz), 7.55-7.51 (4H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 142.0 (2C), 138.7 (2C), 133.9 (2C), 132.9 (2C), 129.6, 128.7 (2C), 128.4 (2C), 127.9 (2C), 126.9, 126.7 (2C), 126.6 (2C), 126.2 (4C), 125.9 (2C). C.sub.26H.sub.18 [M]+ 330.1409, found 330.1401. IR (neat, cm.sup.1): 3066, 2901, 1461, 1011.
Compound P6: 1,4-di(naphthalen-2-yl)benzene
(311) ##STR00084##
(312) Chromatographic purification (50% DCM in hexane) afforded compound P6 (68% yield) as a white solid; m.p. 259-260 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.12 (2H, s), 7.96 (2H, d, J=8.5 Hz), 7.94 (2H, d, J=8.5 Hz), 7.89 (2H, d, J=8.0 Hz), 7.87 (4H, s), 7.85 (2H, dd, J=8.5, 1.6 Hz), 7.54-7.49 (4H, m).). .sup.13C NMR (150 MHz; CDCl.sub.3) 140.3 (2C), 138.2 (2C), 134.0 (2C), 132.9 (2C), 128.7 (2C), 128.5 (2C), 128.1 (4C), 127.9 (2C), 126.6 (2C), 126.2 (2C), 125.9 (2C), 125.7 (2C). C.sub.26H.sub.18 [M]+ 330.1409, found 330.1402. IR (neat, cm.sup.1): 3063, 2905, 1456, 1014.
Example 19. General Procedures for Iodination (O3 & Q1)
(313) ##STR00085## ##STR00086##
(314) A solution of enyne (N3 and P9) (0.34 mmol) in toluene was brought to reflux. A solution of tributyltin hydride (1.2 equiv. for N3 and 3.6 equiv. for P9) and AIBN (0.5 equiv. for N3 and 1.5 equiv. for P9) in toluene was added dropwise to the refluxing solution. The reaction mixture was allowed to reflux for 12 hours. Toluene was evaporated in vacuum and the reaction mixture was dissolved in 2 mL of dichloromethane. Iodine (0.51 mmol for N3 and 1.53 mmol for P9) was added and the reaction mixture stirred at room temperature for 8 hour. The reaction was quenched with a saturated aqueous solution of sodium bisulfite. The aqueous layer was extracted with dichloromethane (4), the combined organic layer was dried over sodium sulfate and concentrated. Chromatographic purification (hexane) afforded compound O3 (yield: 92% white solid) and Q1 (yield: 94% white solid).
Compound P9: 1,3,5-tris((2-((E)-3-methoxyprop-1-en-1-yl)phenyl)ethynyl)benzene
(315) ##STR00087##
(316) Chromatographic purification (15% ethyl acetate in hexane) afforded compound P9 (90% yield) as a light brown oil. Rf=0.6 (20% ethyl acetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.70 (3H, s), 7.61 (3H, d, J=7.7 Hz), 7.55 (3H, d, J=7.5 Hz), 7.34 (3H, t, J=7.5 Hz), 7.26 (3H, t, J=7.8 Hz), 7.21 (3H, d, J=16.0 Hz), 6.43 (3H, dt, J=16.0, 5.5 Hz), 4.20 (6H, d J=5.5 Hz), 3.45 (9H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 38.5 (3C), 134.1 (3C), 132.8 (3C), 130.2 (3C), 129.0 (3C), 128.5 (3C), 127.6 (3C), 125.3 (3C), 124.3 (3C), 121.5 (3C), 92.5 (3C), 89.3 (3C), 73.3 (6C), 58.3 (9C). HRMS (EI): calcd for C.sub.42H.sub.36O.sub.3 [M]+ 588.2664, found 588.2661. IR (neat, cm.sup.1): 3066, 2212, 1471, 949.
Compound P10: 1,3,5-tri(naphthalen-2-yl)benzene
(317) ##STR00088##
(318) Chromatographic purification (40% DCM in hexane) afforded compound P10 (92% yield) as a white solid; m.p. 240-241 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.22 (3H, s), 8.08 (3H, s), 8.01-7.91 (12H, m), 7.57-7.50 (6H, m). .sup.13C NMR (100 MHz; CDCl.sub.3) 142.5 (3C), 138.5 (3C), 133.7 (3C), 132.8 (3C), 128.6 (3C), 128.3 (3C), 127.7 (3C), 126.4 (3C), 126.1 (6C), 125.8 (3C), 125.7 (3C). HRMS (EI): calcd for C.sub.36H.sub.24[M]+ 456.1878, found 456.1871. IR (neat, cm.sup.1): 3098, 2777, 1311, 764.
Example 20. Procedure for the Synthesis of Q3
(319) ##STR00089##
(320) A suspension of aryl iodide (0.292 g, 0.35 mmol), PdCl.sub.2(PPh.sub.3).sub.2 (0.07 mmol), Cu(I) iodide (0.07 mmol) in 8 mL of triethylamine was degassed three times with freeze/pump/thaw technique in a flame-dried round bottom flask. Then 1.0 equiv. of phenyl acetylene (3.1 equiv.; 1.08 mmol) was added dropwise using a syringe. The reaction was allowed to react for 8 hours and monitored by TLC. After total consumption of the aryl iodide, the reaction mixture was filtered through celite and extracted with methylene chloride (330 mL). The organic layer was washed with a saturated solution of ammonium chloride (230 mL), water (230 mL) and dried over anhydrous Na.sub.2SO.sub.4. Solvent was removed in vacuo. The reaction mixture was purified by flash chromatography on silica gel, (eluent: hexane/EtOAc) to afford compound Q3 (86%) as yellow solid.
Compound Q1: 1,3,5-tris(1-iodonaphthalen-2-yl)benzene
(321) ##STR00090##
(322) Chromatographic purification (30% DCM in hexane) afforded compound Q1 (94% yield) as a white solid; m.p>280 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.37 (3H, d, J=8.5 Hz), 7.88 (3H, d, J=8.4 Hz), 7.83 (3H, d, J=8.0 Hz), 7.64-7.61 (6H, m), 7.54 (3H, t, J=7.4 Hz), 7.49 (3H, s). .sup.13C NMR (100 MHz; CDCl.sub.3) 145.9 (3C), 145.5 (3C), 135.2 (3C), 133.8 (3C), 133.3 (3C), 130.1 (3C), 128.8 (3C), 128.5 (3C), 128.3 (3C), 127.9 (126.8 (3C), 104.5 (3C). HRMS (EI): calcd for C.sub.36H.sub.21I.sub.3[M]+ 833.8777, found 833.8772.
Compound Q3: 1,3,5-tris(1-(phenylethynyl)naphthalen-2-yl)benzene
(323) ##STR00091##
(324) Chromatographic purification (30% DCM in hexane) afforded compound Q3 (86% yield) as a white solid; m.p. 212-213 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.66 (3H, d, J=8.3 Hz), 8.35 (3H, s), 7.91 (3H, d, J=8.1 Hz), 7.87 (3H, d, J=8.5 Hz), 7.76 (3H, d, J=8.5 Hz), 7.68 (3H, dt, J=6.9, 1.1 Hz), 7.60-7.56 (3H, m), 7.41-7.39 96H, m), 7.21-7.16 (3H, m), 7.14-7.10 (6H, m). .sup.13C NMR (100 MHz; CDCl.sub.3) 142.7 (3C), 140.8 (3C), 133.8 (3C), 132.5 (3C), 131.7 (6C), 130.8 (3C), 128.8 (3C), 128.4 (6C), 128.3 (6C), 127.8 (3C), 127.4 (3C), 126.9 (3C), 126.6 (3C), 123.5 (3C), 188.9 (3C), 98.3 (3C), 87.7 (3C). HRMS (EI): calcd for C.sub.60H.sub.36[M]+ 756.2817, found 756.2808.
Example 21. General Procedure for the Synthesis of Compounds Q4, Q2, Q5
(325) ##STR00092##
(326) Suzuki Coupling
(327) To a 25 ml flask, 1,3,5-tris(1-iodonaphthalen-2-yl)benzene Q1 (0.20 mmol, 167 mg), aryl boronic acid (0.72 mmol), (10 mol %) Pd(PPh.sub.3).sub.4 (23 mg), K.sub.2CO.sub.3, (276 mg), 2 mL toluene, 0.5 mL EtOH and 0.5 mL H.sub.2O were added. The mixture was degassed by two freeze-pump-thaw cycles and then heated to reflux overnight. Standard work-up and purification by column chromatography (Silica gel, PE/DCM) furnished compounds Q4 (95%), Q2 (92%) and Q5 (30%) as white solids.
Compound Q4: 1,3,5-tris(1-phenylnaphthalen-2-yl)benzene
(328) ##STR00093##
(329) Chromatographic purification (30% DCM in hexane) afforded compound Q4 (95% yield) as a white solid; m.p. 141-142 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.89 (3H, d, J=8.1 Hz), 7.81 (3H, d, J=8.5 Hz), 7.65 (3H, d, J=8.5 Hz), 7.47 (3H, t, J=7.3 Hz), 7.40-7.35 (12H, m), 7.05-7.00 (9H, m), 6.75 (3H, s).). .sup.13C NMR (100 MHz; CDCl.sub.3) 140.9 (3C), 139.3 (3C), 138.4 (3C), 137.6 (3C), 132.9 (3C), 132.7 (3C), 131.9 (6C), 130.4 (3C), 128.6 (3C), 128.1 (6C), 128.0 (3C), 127.5 (3C), 126.9 (3C), 126.8 (3C), 126.3 (3C), 125.8 (3C). HRMS (EI): calcd for C.sub.36H.sub.21I.sub.3[M]+ 684.2817, found 684.2811.
Compound Q2: 1,3,5-tris(1-(4-pentylphenyl)naphthalen-2-yl)benzene
(330) ##STR00094##
(331) Chromatographic purification (30% DCM in hexane) afforded compound Q2 (92% yield) as a white semisolid; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 7.89 (3H, d, J=8.0 Hz), 7.79 (3H, d, J=8.5 Hz), 7.75 (3H, d, J=8.5 Hz), 7.48 (3H, t, J=7.4 Hz), 7.40 (3H, t, J=7.4 Hz), 7.21 (6H, d, J=7.7 Hz), 6.99 (9H, d, J=8.0 Hz), 6.77 (3H, d, J=1.0 Hz) 2.72 (6H, t, J=7.9 Hz), 1.75-1.71 (6H, m), 1.39-1.37 (12H, m), 0.92 (9H, t, J=6.7 Hz). .sup.13C NMR (100 MHz; CDCl.sub.3) 141.4 (3C), 140.8 (3C), 138.4 (3C), 137.6 (3C), 136.5 (3C), 132.9 (3C), 132.8 (3C), 131.9 (6C), 130.4 (3C), 128.7 (3C), 128.0 (6C), 127.9 (3C), 127.3 (3C), 127.1 (3C), 126.1 (3C), 125.7 (3C), 36.0 (3C), 32.0 (3C), 31.5 (3C), 22.8 (3C), 14.3 (3C). HRMS (EI): calcd for C.sub.36H.sub.21I.sub.3[M]+ 894.5165, found 894.5155.
Compound Q5: 1,3,5-tris(1-(2-bromophenyl)naphthalen-2-yl)benzene
(332) ##STR00095##
(333) Chromatographic purification (30% DCM in hexane) afforded compound Q5 (30% yield) as a white solid; m.p. 277-278 C.; Rf=0.5 (50% DCM in hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.90 (3H, d, J=8.2 Hz), 7.88 (3H, d, J=8.5 Hz), 7.62-7.61 (3H, m), 7.48 (3H, t, J=7.4 Hz), 7.40 (3H, t, J=7.4 Hz), 7.34 (3H, d, J=8.4 Hz), 7.28-7.21 (6H, m), 7.15 (3H, d, J=8.5 Hz), 6.99 (3H, s), 6.68-6.66 (3H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 140.7 (6C), 138.3 (3C), 136.4 (3C), 133.4 (3C), 132.7 (3C), 132.6 (3C), 130.0 (3C), 129.4 (3C), 128.6 (3C), 128.4 (6C), 128.3 (3C), 127.2 (3C), 126.6 (3C), 126.5 (3C), 126.2 (3C), 125.9 (3C). HRMS (EI): calcd for C.sub.54H.sub.33Br.sub.3[M]+ 918.0132, found 918.0122.
Example 22. Library of Enynes and Naphthalenes Synthesized
(334)
Compound K21: 2-(p-tolyl)naphthalene
(335) ##STR00096##
(336) Chromatographic purification (hexane) afforded compound K21 (89% yield) as White solid, m. p. 93-95 C. (lit. 92-94 C.). Rf=0.5 (hexane); 1H NMR (400 MHz; CDCl.sub.3) 7.99 (1H, s) 7.79-7.86 (3H, m) 7.69 (2H, dd, J=1.7, 8.5 Hz), 7.59 (2H, d, J=8.1 Hz), 7.39-7.47 (2H, m), 7.24 (2H, d, J=8 Hz), 2.38 (3H, s), .sup.13C NMR (100 MHz; CDCl.sub.3) 138.6, 138.4, 137.3, 129.7, 128.5, 128.3, 127.8, 127.4, 126.4, 125.9, 125.7, 125.6, 21.27.
Compound K22: 2-(4-fluorophenyl)naphthalene
(337) ##STR00097##
(338) Chromatographic purification (hexane) afforded compound K22 (60% yield) as a white solid; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.00 (1H, s), 7.92 (1H, d, J=8.5 Hz), 7.90 (1H, d, J=7.9 Hz), 7.88 (1H, d, J=7.7 Hz), 7.71-7.67 (3H, m), 7.54-7.49 (2H. m), 7.18 (2H, t, J=8.6 Hz). .sup.13C NMR (150 MHz; CDCl.sub.3) 162.8 (d, J=245.2 Hz), 137.8, 137.5, 133.9, 132.8, 129.2 (2C, d, J=7.9 Hz), 128.7, 128.3, 127.9, 126.6, 126.2, 125.9, 125.6, 115.9 (2C, d, J=21.2 Hz), HRMS (ED: calcd for C.sub.16H.sub.11F [M]+ 222.0845, found 222.0841. IR (neat, cm.sup.1): 3059, 1602, 1512, 1500, 1221, 1157, 1094, 822, 747.
Compound K23: 4-(naphthalen-2-yl)benzonitrile
(339) ##STR00098##
(340) Chromatographic purification (5% DCM in hexane) afforded compound K23 (82% yield) as a white solid. Rf=0.5 (5% DCM in hexane); m.p. 127-129 C.; 1H NMR (300 MHz, CDCl.sub.3) 8.05 (1H, s), 7.92 (3H, m), 7.81 (2H, d, J=8.4 Hz), 7.75 (2H, d, J=8.4 Hz), 7.70 (1H, dd, J=8.4, 1.5 Hz), 7.53 (2H, m); 13CNMR (75 MHz, CDCl.sub.3) 145.5, 136.3, 133.4, 133.1, 132.6, 128.9, 128.3, 127.9, 127.6, 126.7, 126.6, 126.5, 124.8, 118.9, 110.9.
Compound K24: 1-(4-(naphthalen-2-yl)phenyl)ethan-1-one
(341) ##STR00099##
(342) Chromatographic purification (hexane) afforded compound K24 (87% yield) as pale yellow solid: m.p.: 129-130 C.; Rf=0.5 (hexane); 1H NMR (400 MHz, CDCl.sub.3): 8.09-8.07 (3H, m), 7.95-7.87 (3H, m), 7.83 (2H, d, J=8.8 Hz), 7.77-7.75 (1H, dd, J=8.4 Hz), 7.55-7.51 (2H, m), 2.66 (3H, s). 13C NMR (100 MHz, CDCl.sub.3): 197.9, 145.8, 137.2, 135.9, 133.6, 133.1, 129.1, 128.8, 128.4, 127.8, 127.6, 126.7, 126.6, 126.5, 125.3, 26.8.
Compound K25: 2-(4-methoxyphenyl)naphthalene
(343) ##STR00100##
(344) Chromatographic purification (hexane) afforded compound K25 (78% yield) as a white solid; m. p. 130-131 C.; Rf=0.5 (hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 8.04-7.97 (1H, m), 7.92-7.83 (3H, m), 7.73 (1H, dd, J=8.5, 1.9 Hz), 7.71-7.64 (2H, m), 7.54-7.42 (2H, m), 7.08-6.99 (2H, m), 3.88 (3H, s). .sup.13C NMR (CDCl3, 100 MHz) 159.5, 138.4, 134.0, 133.9, 132.6, 128.7, 128.6 (2C), 128.30, 127.9, 126.5, 125.9 25.7, 125.3, 114.5 (2C), 55.6. HRMS (EI): calcd for C.sub.17H.sub.15O [M]+ 234.1045, found 234.1038. IR (neat, cm.sup.1): 2959, 2921, 2826, 1283, 1038, 822, 814, 746, 694, 689.
Compound K26: 2-(naphthalen-2-yl)thiophene
(345) ##STR00101##
(346) Chromatographic purification (hexane) afforded compound K26 (65% yield) as a yellow solid. .sup.1H NMR (300 MHz; CDCl.sub.3) 8.00 (1H, s), 7.67-7.79 (4H, m), 7.36-7.45 (3H, m), 7.24 (1H, dd, J=1.2, 5.1 Hz), 7.05 (1H, dd, J=3.6, 5.1 Hz).sup.13C NMR (75 MHz; CDCl.sub.3): 144.5, 133.8, 132.8, 131.9, 128.6, 128.2, 128.1, 127.8, 126.6, 126.0, 125.1, 124.5, 124.3, 123.6.
Compound K27: 2-(naphthalen-2-yl)pyridine
(347) ##STR00102##
(348) Chromatographic purification (hexane) afforded compound K27 (78% yield) as a yellow oil; Rf=0.2 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.76 (1H, d, J=3.4 Hz), 8.49 (1H, s), 8.15 (1H, dd, J=8.6, 1.6 Hz), 7.97-7.94 (2H, m), 7.89-7.87 (2H, m), 7.79 (2H, dt, J=7.6, 1.7 Hz), 7.53-7.50 (2H, m), 7.28-7.26 (1H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 157.6, 150.0, 137.0, 136.9, 133.9, 133.7, 128.9, 128.7, 127.9, 126.7, 126.5 (2C), 124.8, 122.4, 121.0. HRMS (ED: calcd for C.sub.15H.sub.11N [M]+ 205.0891, found 205.0888. IR (neat, cm.sup.1): 3078, 2922, 1488, 877.
Compound K28: 5-(naphthalen-2-yl)pyrimidine
(349) ##STR00103##
(350) Chromatographic purification (5% ethylacetate in hexane) afforded compound K28 (68% yield) as a yellow solid; m. p. 108 C. Rf=0.2 (5% ethylacetate in hexane); .sup.1H NMR (400 MHz; CDCl.sub.3) 9.24 (1H, s), 9.07 (2H, s), 8.04 (1H, d, J=1.4 Hz), 7.99 (1H, d, J=8.5 Hz), 7.94-7.89 (2H, m), 7.68 (1H, dd, J=8.5, 1.8 Hz), 7.58-7.53 (2H, m). .sup.13C NMR (100 MHz; CDCl.sub.3) 157.6, 155.3 (2C), 134.5, 133.7, 133.4, 131.7, 129.6, 128.5, 128.0, 127.2, 127.1, 126.6, 124.5. HRMS (ED: calcd for C.sub.14H.sub.10N.sub.2 [M]+ 206.0844, found 206.0838. IR (neat, cm.sup.1): 3051, 2778, 1476, 821.
Compound K29: 7-(pyridin-2-yl)quinolone
(351) ##STR00104##
(352) Chromatographic purification (hexane) afforded compound K29 (78% yield) as a white solid; Rf=0.2 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.96 (1H, dd, J=4.1, 1.6 Hz), 8.77 (1H, dd, J=4.8, 0.7 Hz), 8.63 (1H, s), 8.35 (1H, dd, J=8.5, 1.6 Hz), 8.20 (1H, d, J=7.9 Hz), 7.95 (2H, t, J=8.3 Hz), 7.83 (1H, m), 7.44-7.42 (1H, m), 7.32-7.29 (1H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 156.7, 150.9, 149.9, 148.5, 140.5, 137.0, 135.8, 128.5, 128.3, 127.4, 125.6, 122.6, 121.5, 121.2. HRMS (ED: calcd for C.sub.14H.sub.10N.sub.2 [M]+ 206.0844, found 206.0838. IR (neat, cm.sup.1): 3102, 2878, 1234, 798.
Compound K30: 2-(o-tolyl)naphthalene
(353) ##STR00105##
(354) Chromatographic purification (hexane) afforded compound K30 (82% yield) as colorless oil. Rf=0.5 (hexane); 1H NMR (300 MHz, CDCl.sub.3): 7.79-7.83 (m, 3H), 7.74 (s, 1H), 7.42-7.46 (m, 3H), 7.24-7.31 (m, 4H), 2.28 (s, 3H). 13C NMR (75.4 MHz, CDCl.sub.3): 141.9, 139.6, 135.6, 133.4, 132.3, 130.4, 130.1, 128.0, 127.83, 127.77, 127.72, 127.5, 127.4, 126.2, 125.9, 20.4.
Compound K31: 2-([1,1-biphenyl]-2-yl)naphthalene
(355) ##STR00106##
(356) Chromatographic purification (hexane) afforded compound K31 (88% yield) as a white solid. Rf=0.4 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.77-7.76 (3H, m), 7.60 (1H, d, J=8.5 Hz), 7.56-7.54 (1H. m), 7.49-7.43 (5H, m), 5.04 (5H, s), 7.13 (1H, dd, J=8.5, 1.7 Hz). .sup.13C NMR (150 MHz; CDCl.sub.3) 141.7, 141.0, 140.6, 139.5, 133.6, 132.3, 131.2, 130.9, 130.1 (2C), 128.6 (2C), 128.2 (3C), 127.8 (3C), 127.2, 126.7, 126.1, 126.0. C.sub.22H.sub.16[M]+ 280.1252, found 280.1250. IR (neat, cm.sup.1): 3087, 2189, 1495.
Compound K32: 2,2-binaphthalene
(357) ##STR00107##
(358) Chromatographic purification (hexane) afforded compound K32 (78% yield) as a white solid; m.p. 187-188 C.; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.19 (2H, d, J=1.0 Hz), 7.98-7.94 (4H, m), 7.91-7.89 (4H, m), 7.55-7.50 (4H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 138.6 (2C), 133.9 (2C), 132.9 (2C), 128.7 (2C), 128.4 (2C), 127.9 (2C), 126.6 (2C), 126.3 (2C), 126.2 (2C), 125.9 (2C). HRMS (EI): calcd for C.sub.20H.sub.14 [M]+ 254.1096, found 254.1094. IR (neat, cm.sup.1): 3054, 2921, 1923, 1593, 1129.
Compound K33: 1,2-binaphthalene
(359) ##STR00108##
(360) Chromatographic purification (hexane) afforded compound K33 (43% yield) as a white solid; m.p. 137-139 C.; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 7.97-7.90 (7H, m), 7.66-7.64 (1H, m), 7.59-7.50 (5H, m), 7.45-7.42 (1H, m). .sup.13C NMR (150 MHz; CDCl.sub.3) 140.4, 138.5, 134.0, 133.6, 132.8, 132.0, 128.9, 128.7, 128.5, 128.3, 128.0 (2C), 127.9, 127.4, 126.5, 126.3 (2C), 126.2, 126.0, 125.6. HRMS (EI): calcd for C.sub.20H.sub.14 [M]+ 254.1096, found 254.1090. IR (neat, cm.sup.1): 3039, 2921, 1928, 1503, 1131.
Compound K34: 9-(naphthalen-2-yl)anthracene
(361) ##STR00109##
(362) Chromatographic purification (hexane) afforded compound K34 (15% yield) as a white solid; Rf=0.5 (hexane); .sup.1H NMR (600 MHz; CDCl.sub.3) 8.54 (1H, S), 8.08-8.00 (4H, m), 7.93-7.88 (3H, m), 7.68 (2H, d, J=8.8 Hz), 7.61-7.55 (3H, m), 7.47 (2H, t, J=7.0 Hz), 7.32 (2H, t, J=7.3 Hz). .sup.13C NMR (150 MHz; CDCl.sub.3) 136.8, 136.3, 133.4, 132.7, 131.4, 130.4, 130.1, 129.5, 128.4, 128.2, 128.1, 127.9, 126.8, 126.7, 126.4, 126.2, 125.4, 125.1. HRMS (EI): calcd for C.sub.24H.sub.16 [M]+ 304.1252, found 304.1250.
(363) When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles a, an, the and said are intended to mean that there are one or more of the elements. The terms comprising, including and having are intended to be inclusive and mean that there may be additional elements other than the listed elements.
(364) In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
(365) As various changes could be made in the above products and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.