METHODS OF PREPARING OXA-BICYCLOALKENE

Abstract

Disclosed is a method of preparing an oxa-bicycloalkene via the reaction of a cycloalkanone and an allyl alcohol compound in the presence of an organic acid, a manganese catalyst, and oxygen at a predetermined temperature.

Claims

1. A method of preparing an oxa-bicycloalkene comprising reacting (i) a cycloalkanone and (ii) an allyl alcohol compound in the presence of an organic acid, a manganese catalyst, and oxygen at a temperature of 60 to 200 C. for 1 to 24 hours.

2. The method of claim 1, wherein the cycloalkanone has 4 to 16 ring atoms selected from carbon, oxygen, sulfur, and nitrogen; the allyl alcohol compound is allyl alcohol or an ester, ether, oxime, or silyl of allyl alcohol; the organic acid is acetic acid, and the manganese catalyst is a manganese (II) compound selected from the group consisting of manganese (II) acetate, manganese (II) sulfate, manganese (II) chloride, manganese (II) bromide, manganese (II) iodide, manganese (II) oxide, manganese (II) triflate, and manganese (II) perchlorate.

3. The method of claim 2, wherein the allyl alcohol compound is allyl alcohol or allyl acetate, and the manganese catalyst is supported on a zeolite, aluminophosphate, polyoxometallate, or combination thereof.

4. The method of claim 1, wherein the molar ratio between the cycloalkanone and the allyl alcohol compound is 20:1 to 1:6, the molar ratio between the organic acid and the allyl alcohol is 100:1 to 1:1, and the molar ratio between the manganese catalyst and the allyl alcohol is 1:1000 to 1:1.

5. The method of claim 1, wherein the reaction is performed in the presence of peracetic acid, the molar ratio between the peracetic acid and the allyl alcohol compound is 1:1 to 100:1, and the peracetic acid is added to the reaction or generated in-situ from the reaction of acetic acid in the presence of the manganese catalyst.

6. The method of claim 1, wherein the oxygen is provided as air, oxygen-enriched air, or oxygen gas in a pressure of 1 to 24 atmospheres.

7. The method of claim 1, wherein the reaction is performed in the absence of a solvent.

8. The method of claim 1, wherein the oxa-bicycloalkene has the following Formula (I): ##STR00010## the cycloalkanone has the following Formula (II): ##STR00011## and the allyl alcohol compound has the following Formula (III): ##STR00012## in which m is 0-11; each of R.sub.1 to R.sub.13, independently, is H, OH, SH, CN, NO.sub.2, NH.sub.2, halo, C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10 alkenyl, C.sub.2-C.sub.10 alkynyl, C.sub.1-C.sub.10 heteroalkyl, C.sub.3-C.sub.8 cycloalkyl, C.sub.1-C.sub.8 heterocycloalkyl, C.sub.1-C.sub.10 alkoxy, C.sub.1-C.sub.10 alkylthio, C.sub.1-C.sub.10 acyl, C.sub.1-C.sub.10 acyloxy, aryl, aryloxy, arylthio, C.sub.1-C.sub.10 arylalkyl, heteroaryl, heteroaryloxy, heteroarylthio, C.sub.1-C.sub.10 heteroarylalkyl, C.sub.1-C.sub.10 alkylamino, C.sub.1-C.sub.20 dialkylamino, arylamino, diarylamino, heteroarylamino, diheteroarylamino, C.sub.1-C.sub.10 alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, C.sub.1-C.sub.10 alkylsulfonamide, arylsulfonamide, heteroarylsulfonamide, C.sub.1-C.sub.10 alkylmercapto, or arylmercapto; and R.sub.14 is H, C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10 alkenyl, C.sub.2-C.sub.10 alkynyl, C.sub.1-C.sub.10 heteroalkyl, C.sub.3-C.sub.8 cycloalkyl, C.sub.3-C.sub.8 heterocycloalkyl, C.sub.1-C.sub.10 alkoxy, C.sub.1-C.sub.10 alkylthio, C.sub.1-C.sub.10 acyl, C.sub.1-C.sub.10 acyloxy, aryl, aryloxy, arylthio, C.sub.1-C.sub.10 arylalkyl, heteroaryl, heteroaryloxy, C.sub.1-C.sub.10 heteroarylalkyl, C.sub.1-C.sub.10 alkylamino, C.sub.1-C.sub.20 dialkylamino, arylamino, diarylamino, heteroarylamino, diheteroarylamino, C.sub.1-C.sub.10 alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, C.sub.1-C.sub.10 alkylsulfonamide, arylsulfonamide, heteroarylsulfonamide, C.sub.1-C.sub.10 alkylmercapto, or arylmercapto; each of cycloalkyl, heterocycloalkyl, aryl, arylalkyl, heteroaryl, and heteroarylalkyl, independently, is unsubsituted or substituted with C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10alkenyl, C.sub.2-C.sub.10alkynyl, C.sub.3-C.sub.8 cycloalkyl, C.sub.1-C.sub.8 heterocycloalkyl, C.sub.1-C.sub.10 alkoxy, C.sub.1-C.sub.10 alkylthio, aryl, aryloxy, arylthio, heteroaryl, heteroaryloxy, heteroarylthio, amino, C.sub.1-C.sub.10 alkylamino, C.sub.1-C.sub.20 dialkylamino, arylamino, diarylamino, heteroarylamino, diheteroarylamino, C.sub.1-C.sub.10 alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, C.sub.1-C.sub.10 alkylsulfonamide, arylsulfonamide, heteroarylsulfonamide, hydroxyl, halogen, mercapto, C.sub.1-C.sub.10 alkylmercapto, arylmercapto, cyano, nitro, acyl, acyloxy, carboxyl, amido, carbamoyl, or carboxylic ester; and each of alkyl, alkenyl, alkynyl, alkylene, and alkenylene is unsubstituted or substituted with C.sub.3-C.sub.8 cycloalkyl, C.sub.1-C.sub.8 heterocycloalkyl, C.sub.1-C.sub.10alkoxy, C.sub.1-C.sub.10 alkylthio, aryl, aryloxy, arylthio, heteroaryl, heteroaryloxy, heteroarylthio, amino, C.sub.1-C.sub.10 alkylamino, C.sub.1-C.sub.20 dialkylamino, arylamino, diarylamino, heteroarylamino, diheteroarylamino, C.sub.1-C.sub.10 alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, C.sub.1-C.sub.10 alkylsulfonamide, arylsulfonamide, heteroarylsulfonamide, hydroxyl, halogen, mercapto, C.sub.1-C.sub.10 alkylmercapto, arylmercapto, cyano, nitro, acyl, acyloxy, carboxyl, amido, carbamoyl, or carboxylic ester.

9. The method of claim 8, wherein the oxa-bicycloalkene is 3,4,5,6,7,8,9,10,11,12,13,14-dodecahydro-2H-cyclododeca[b]pyran having the following Formula (IV): ##STR00013## the cycloalkanone is cyclododecanone of Formula (V): ##STR00014## and the allyl alcohol compound is allyl acetate or allyl alcohol.

10. The method of claim 9, wherein the cycloalkanone has 4 to 16 ring atoms selected from carbon, oxygen, sulfur, and nitrogen; the allyl alcohol compound is allyl alcohol or an ester, ether, oxime, or silyl of allyl alcohol; the organic acid is acetic acid, and the manganese catalyst is a manganese (II) compound selected from the group consisting of manganese (II) acetate, manganese (II) sulfate, manganese (II) chloride, manganese (II) bromide, manganese (II) iodide, manganese (II) oxide, manganese (II) triflate, and manganese (II) perchlorate.

11. The method of claim 10, wherein the allyl alcohol compound is allyl alcohol or allyl acetate, and the manganese catalyst is supported on a zeolite, aluminophosphate, polyoxometallate, or combination thereof.

12. The method of claim 9, wherein the molar ratio between the cycloalkanone and the allyl alcohol compound is 20:1 to 1:6, the molar ratio between the organic acid and the allyl alcohol is 100:1 to 1:1, and the molar ratio between the manganese catalyst and the allyl alcohol is 1:1000 to 1:1.

13. The method of claim 9, wherein the reaction is performed in the presence of peracetic acid, the molar ratio between the peracetic acid and the allyl alcohol compound is 1:1 to 100:1, and the peracetic acid is added to the reaction or generated in-situ from the reaction of acetic acid in the presence of the manganese catalyst.

14. The method of claim 9, wherein the oxygen is provided as air, oxygen-enriched air, or oxygen gas in a pressure of 1 to 24 atmospheres.

15. The method of claim 9, wherein the reaction is performed in the absence of a solvent.

16. The method of claim 1, wherein the reaction is performed in a batch reactor or a continuous reactor system.

17. The method of claim 16, wherein the reaction is performed in a continuous reactor system, and the manganese catalyst is a fixed-bed catalyst.

18. The method of claim 17, wherein the continuous reactor system is a single Continuous Stirred Tank Reactor (CSTR), a multiple CSTRs in series, or a microreactor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention is based on surprising discoveries of the versatile utility of inexpensive manganese salts, in particular manganese (II) acetate, in the synthesis of oxa-bicycloalkene by reacting a cycloalkanone and an allyl alcohol compound. The preparations are particularly of interest in the manufacture of fragrance ingredients such as 3,4,5,6,7,8,9,10,11,12,13,14-dodecahydro-2H-cyclododeca[b]pyran (BCP).

[0031] In some embodiments, the preparation is shown in Scheme 3 below.

##STR00008##

[0032] In this scheme, m and R.sub.1-R.sub.14 are defined above. The reaction shown in Scheme 3 is typically carried out in a one-step process without the necessity of separating an intermediate. In general, cycloalkanone of Formula (II) is added to a reaction vessel and mixed with an allyl alcohol compound of Formula (III), together with a manganese catalyst and an organic acid. Oxygen gas is then introduced to the reaction vessel with seal and the reaction is then carried out at a pressure of 0.1 to 24 atmospheres (e.g., 1 to 24 atmospheres and 1 to 12 atmospheres) with a lower limit of 0.1, 0.5, or 1 atmosphere and an upper limit of 24, 22, 20, 18, 16, 15, 12, 10, 9, 8, 6, and 5 atmospheres. Preferably, the reaction vessel is purged with the oxygen gas before the temperature is raised to a predetermine reaction temperature and kept at that temperature for a predetermined period of time to cause the reaction between the cycloalkanone and the allyl alcohol compound. The product of oxa-bicycloalkene can be readily isolated either by distillation or by column chromatography.

[0033] The cycloalkanone of Formula (II) can have 4 to 16 atoms, preferably between 10 to 14 atoms, e.g., a macrocyle ketone. The cycloalkanone can be optionally substituted. Namely, each of R.sub.1 to R.sub.8 independently is a chemical group listed in the summary section above. Preferably, each of R.sub.1 to R.sub.8, independently, is H, or a lower alkyl having 1 to 6 (e.g., 1 to 4) carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl. In addition, two or more R.sub.1 and R.sub.8, together with the atom(s) they connect to, can form a ring. As such, the cycloalkanone can be a single ring, fused bicylic ring, fused tricyclic ring, etc. In a preferred embodiment, each of R.sub.1 to R.sub.8 is H, and the ring has 10, 11, 12, 13, or 14 carbon atoms. Based on the mass of allyl alcohol compound (namely, the mass of the allyl alcohol compound being 1 equivalent), the mass of the cycloalkanone can ranges from 0.2 to 10 equivalents (e.g., 1 to 10 equivalents, and 1 to 4 equivalents) with the lower limit of 0.2, 0.5, 1, or 3 equivalents and the upper limit of 4, 5, 6, 7, 8, or 9 equivalents.

[0034] One specific example of this process is the preparation of BCP from cyclododecanone (CDDK) and allyl acetate (or allyl alcohol) as shown in Scheme 4 below.

##STR00009##

[0035] In some embodiments, the manganese catalyst is a manganese(II) salt in anhydrous or hydrated form, including acetates, sulfates, chlorides, bromides, oxides, triflates, and perchlorates. The manganese catalyst can be supported on a solid such as Mn (II)-zeolites, Mn(II)-aluminophosphates (ALPOs) and Mn(II)-polyoxometallates. Preferably, manganese (II) acetate in hydrated form is used. The mass of the manganese catalyst is 0.1 to 100 mol %, preferably 0.5 to 4 mol % based on the mass of the allyl alcohol compound.

[0036] In some embodiments, oxygen is used as air or a pure gas (e.g., containing oxygen at least 80 wt %, at least 85 wt %, at least 90 wt %, at least 95 wt %, at least 98 wt %, at least 99 wt %, at least 99.5 wt %, or at least 99.9 wt %). The oxygen can be added to the reaction mixture at a pressure of 0.1 to 24 atmospheres (e.g., 1 to 12 atmospheres).

[0037] Suitable organic acids include acetic acid (AcOH), lactic acid, succinic acid, propionic acid, butyric acid, citric acid, benzoic acid, sorbic acid, tartaric acid, malic acid, gluconic acid, fumaric acid, and combination thereof. A preferred organic acid is acetic acid, e.g., a glacial acetic acid. The organic acid is typically presented in the reaction mixture at a level of 1 to 100 equivalents (e.g., 1 to 5 equivalents) based on the mass of the allyl alcohol compound, with an upper limit of 100, 80, 50, 40, 30, 25, 20, 15, 12, 10, 8, and 5 equivalents.

[0038] The reaction is carried out with or without a solvent. Suitable solvents are ethyl acetate, acetonitrile, malononitrile, and combinations thereof.

[0039] In some embodiments, the reaction is performed without adding any peroxide compound to the reaction mixture to ensure safety in a manufacturing setting. Peracetic acid may be generated in-situ with manganese catalysts, oxygen and acetic acid. In other embodiments, a relatively safe peroxide such as peracetic acid is added to the reaction mixture in the form of a commercial solution in water/sulfuric acid. The peracetic acid is added to the reaction at a level of 1 to 100 equivalents (e.g., 5 to 10 equivalents) based on the mass of the allyl alcohol compound.

[0040] In some embodiments, the reaction is performed at 60 to 200 C. (e.g., 80 to 200 C., and 100 to 130 C.) for a period of 1 to 24 hours (e.g., 2 to 20 hours and 2 to 10 hours) when operating in a batch or semi-continuous mode. If the reaction is performed in a continuous reactor system, the contact time is typically between 0.1 to 10 hours, and preferably 0.5 to 5 hours. The contact time is calculated as the weight of catalyst (g) divided by the flow rate of the starting allyl alcohol compound (g/h) in the continuous reactor.

[0041] Herein, this application discloses a convenient and operationally simple means of effecting the cyclization of cycloalkanone with an allyl alcohol compound in a single step using a manganese catalyst, an organic acid, and oxygen.

[0042] The results obtained for the coupling of cyclododecanone (CDDK) and one of the two allyl alcohol compounds (e.g., allyl alcohol and allyl acetate) are shown in Table 1 below. These examples showed reactions conducted at various reaction temperatures, reaction time, oxygen pressures, the ratios between the cycloalkanone and allyl alcohol compound, and the molar % of the manganese catalyst based on the mass of the allyl alcohol compound. Mn(OAc).sub.2.4H.sub.2O was used as a catalyst. The yield was calculated based on the allyl alcohol compound. Unexpectedly, BCP was obtained at a high yield (e.g., 45%) and a high selectivity (e.g., 95%). Selectivity refers to the molar percentage of BCP as compared to the mass of the allyl alcohol compound consumed in the reaction.

TABLE-US-00001 TABLE 1 Preparation of BCP Mn O.sub.2 T Time Yield S Example Allyl Ratio.sup.d (mol %) (atm) ( C.) (h) (%) (%) 1.sup.a OH 4:1 25 1 80 4 13 >95 2.sup. OAc 4:1 25 1 80 4 22 73 3.sup. OAc 10:1 2.5 10 110 4 39 88 4.sup. OAc 10:1 2.5 10 110 4 42 87 5.sup. OAc 10:1 0.5 10 110 18 45 90 6.sup.a OH 10:1 2.5 10 110 4 15 >95 7.sup.b OAc 4:1 1 10 110 9 37 88 8.sup.c OAc 2:1 1 10 110 5 29 85 9.sup.c OAc 4:1 1 10 110 5 33 89 10.sup.c OAc 2:1 1 10 130 3.5 29 88 11.sup.c OAc 4:1 1 10 130 3.5 41 87 .sup.aBy-products from alcohol oxidation were found. .sup.bAcOH (5M). .sup.cAcOH (2M). .sup.dMolar ratio CDDK/allyl alcohol compound. .sup.e Glacial AcOH is used in Examples 1-6.

[0043] Only a catalytically effective amount of manganese catalyst is required for the reaction. In addition, the manganese catalyst is much safer to handle than the peroxides used in traditional processes of preparing BCP. See U.S. Pat. No. 3,856,815. The reaction temperature is kept moderate at 80 to 130 C.

[0044] The manganese catalyst can be reused. Catalyst Mn(OAc).sub.2.4H.sub.2O, as used in these examples, is soluble in the reaction medium. It was quantitatively recovered after distillation of the reaction mixture or by precipitation with a non-polar solvent (e.g., hexane, ether, and dichloromethane). Without any additional treatment, the manganese acetate so recovered was reused in the reaction without loss of its catalytic activity.

[0045] In addition, Mn(OAc).sub.2.4H.sub.2O can be supported on a solid in order to get a filterable catalyst, and/or amenable for a continuous flow process. Preferentially, Mn(II) acetate hydrate is incorporated on -Al.sub.2O.sub.3, silica, titania or zirconia by impregnation, or on 12R pore zeolites (e.g., H-Y zeolite commercially available as CBV-720 and CBV-740 from Zeolyst International, Valley Forge, Pa.; HBeta zeolite commercially available as CP811C-300 from Zeolyst International; and mordenite zeolite commercially available as CBV10A and CBV21A from Zeolyst International) by the exchange method to obtain, for instance, a Mn.sup.2+-HBeta zeolite. Other solid supports include ALPOs and poly-oxometallates. These solid-supported catalysts effectively catalyze the reaction and can be readily recovered from the reaction mixture by simple filtration.

[0046] The term alkyl, as used herein, means a straight or branched-chain saturated hydrocarbon group containing from 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms (lower alkyl), and even more preferably 1 to 4 carbon atoms, which is connected with the rest of the molecular moiety through a single bond. Representative examples include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, etc.

[0047] The term alkoxy, as used herein, means an O-alkyl group, where alkyl is as defined herein. Representative examples of alkoxy include methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy, etc.

[0048] The term aryl, as used herein, means an aromatic hydrocarbon group composed of 6 to 14, preferably 6 to 10, carbon atoms. Representative examples of aryl include phenyl and naphthyl. Unless specified in the present application, the term aryl may be substituted by one or more substituents, such as C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 haloalkyl, C.sub.1-C.sub.6 alkoxy, etc.

[0049] The term arylalkyl refers to an alkyl group substituted by one or more aryl groups, wherein alkyl and aryl are as defined herein. Representative examples of arylalkyl include, but are not limited to, benzyl, 2-phenylethyl, diphenylmethyl, and naphth-2-ylmethyl, etc.

[0050] The term carboxyl, as used herein, means a C(O)O.sup. or CO.sub.2H group.

[0051] The term cycloalkyl, as used herein, means a cyclic hydrocarbon group containing from 3 to 24 carbon atoms (e.g., 3 to 20, and 5 to 18 carbon atoms), where such groups can be saturated or unsaturated, but not aromatic. In certain embodiments, cycloalkyl groups are preferably fully saturated. Examples of cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclohexenyl, etc.

[0052] The term cycloalkylalkyl, as used herein, means alkyl group substituted by one or more cycloalkyl group, wherein alkyl and cycloalkyl are as defined herein.

[0053] The term acyl or acylated means C(O)R.sup.5, where R.sup.5 is defined above.

[0054] The term halo or halogen refers to F, Cl, Br, and I, preferably Cl or Br.

[0055] The term haloalkyl refers to an alkyl group substituted by one or more halogen atoms.

[0056] The singular forms a, an, and the include plural reference, and vice versa, unless the context clearly dictates otherwise.

[0057] The term about, when used in front of a number, indicates that the number can fluctuate for 10%, preferably within 5%. The values and dimensions disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such value is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a value disclosed as 50% is intended to mean about 50%.

[0058] All parts, percentages and proportions refer to herein and in the claims are by weight unless otherwise indicated.

[0059] The terms g, mg, and g refer to gram, milligram, and microgram, respectively. The terms L and mL refer to liter and milliliter, respectively. The term Mol and mmol refer to mole and millimole, respectively.

[0060] The invention is described in greater detail by the following non-limiting examples. Without further elaboration, it is believed that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent.

EXAMPLES

[0061] General reaction procedure. A predetermined amount of Mn(II) catalyst and cyclododecanone (e.g., 12 mmol) were added to a 6-mL vial equipped with a magnetic stirrer. Acetic acid (AcOH; 1 mL) and the allyl alcohol compound (allyl alcohol or allyl acetate) were then added and the vial was sealed and connected to a manometer. Oxygen was introduced through a valve to reach a predetermined pressure (1 to 24 atmospheres) and then liberated to purge the vial. This operation was repeated twice to finally leave the required oxygen atmosphere (c.a. 1 to 6 mmol). The vial was placed in an oil-bath at a predetermined temperature and stirred for a predetermined period of time. Subsequently, the vial was cooled, the remaining oxygen was liberated, and the mixture was analyzed by a gas chromatography (GC) after dilution in dichloromethane. The product was isolated either by distillation or by flash column chromatography on silica gel, eluting with hexanes-ethyl acetate mixtures.

[0062] The desired product BCP was isolated and characterized with GC-MS, .sup.1H NMR, and .sup.13C NMR after column chromatography. Rf (hexane-EtOAc, 4:1)=0.75. GC-MS, m/z 222.2 [M].sup.+. .sup.1H NMR (CDCl.sub.3, 300 MHz; in ppm, J in Hz): 3.89 (t, J=5.0, 2H), 2.16 (t, J=6.7, 2H), 2.03 (t, J=7.0, 2H), 1.94 (t, J=6.3, 2H), 1.83 (quint, J=5.7, 2H), 1.45-1.20 (mult, 16H). .sup.13C NMR (CDCl.sub.3, 75 MHz; in ppm): 148.5 (C), 107.0 (C), 65.5 (CH.sub.2), 37.0 (CH.sub.2), 30.5-21.8 (11CH.sub.2).

[0063] The major impurity of the reaction was 3-(2-oxocyclododecyl)propyl acetate, which was confirmed by .sup.1H NMR and .sup.13C NMR analysis.

Examples 1-9

[0064] BCP was prepared following the general procedure with the amount of reagents indicated in Table 1 above, Examples 1-9, respectively.

Example 10

[0065] Reaction procedure for Example 10 shown in Table 1. Mn(OAc).sub.2.4H.sub.2O (2.8 mg, 1 mol %) and CDDK (430 mg, 2.4 mmol) were added to a 6-mL vial equipped with a magnetic stirrer. AcOH (0.5 mL) and allyl acetate (128 L, 1.2 mmol) were then added and the vial was sealed, connected to a manometer. Oxygen was introduced through a valve to reach 10 atmospheres and liberated to purge the vial. This operation was repeated twice to finally fill the vial with oxygen at a pressure of 10 atmospheres (about 3 mmol). The vial was placed in an oil-bath at 130 C. and stirred for 3.5 h. After that, the vial was cooled, the remaining oxygen was liberated, and the mixture was analyzed by GC after dilution in dichloromethane.

Example 11

[0066] Reaction procedure for Example 11 shown in Table 1. MnOAc).sub.2.4H.sub.2O (2.8 mg, 1 mol %) and CDDK (860 mg, 4.8 mmol for 4:1) were added to a 6-mL vial equipped with a magnetic stirrer. After AcOH (0.5 mL) and allyl acetate (128 L, 1.2 mmol) were added, the vial was sealed, connected to a manometer, and purged with oxygen twice. Subsequently, the vial was filled with oxygen at a pressure of 10 atmospheres (about 3 mmol) and heated in an oil-bath at 130 C. for 3.5 hours. After that, the vial was cooled, remaining oxygen liberated, and the mixture was analyzed by GC after dilution in dichloromethane.

[0067] All references cited herein are incorporated by reference in their entirety. The foregoing examples and description of certain preferred embodiments should be taken as illustrating, rather than as limiting, the present invention. As would be readily appreciated by a person skilled in the art, numerous variations and combinations of the features set forth above can be utilized without departing from the present invention, which are all encompassed by the present invention.