CATALYSTS AND PROCESSES FOR STEREOSELECTIVE RING-OPENING POLYMERIZATION
20260108869 ยท 2026-04-23
Inventors
Cpc classification
B01J31/2217
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
Provided is a chelate complex comprising (a) a rare earth metal cation M; (b) a chelate ligand of formula (CL1 A) or (CL1 B) c) at least one anionic nucleophilic ligand LN which is coordinated as a further ligand to the rare earth metal cation; and d) optionally one or more neutral donor ligands LD coordinated as ligands to the rare earth metal cation. Moreover, provided are a process for the preparation of a chelate complex, a process for the preparation of a polymer comprising a polymerization reaction of chiral cyclic ester monomers, and a poly(3-hydroxy butyrate) polymer which can be provided by the process.
##STR00001##
Claims
1. A chelate complex comprising: a) a rare earth metal cation M; b) a chelate ligand of formula (CL1A) or (CL1B) ##STR00054## wherein the chelate ligand is coordinated via the two nitrogen atoms and the two oxygen atoms shown in the formulae to the rare earth metal cation, R.sup.1a and R.sup.1b independently represent a sterically demanding group comprising 6 or more skeleton atoms, and optionally, R.sup.1a and R.sup.1b may be linked to each other to provide a divalent organic residue, R.sup.2a and R.sup.2b are independently selected from hydrogen, C1-C20 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 10 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, a group of the formula (S-1) ##STR00055## wherein R.sup.S1 is selected from a C1-C9 divalent alkyl group which is optionally substituted, O and a OC1-C8 divalent alkyl group which is optionally substituted, and R.sup.AR1 is selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted, and a group of the formula (S-2) ##STR00056## wherein R.sup.S2 is selected from a C1-C6 trivalent alkyl group which is optionally substituted, O and a OC1-C5 trivalent alkyl group which is optionally substituted, and R.sup.AR2 and R.sup.AR3 are independently selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted, R.sup.3a and R.sup.3b are, independently for each occurrence, selected from hydrogen, C1-C10 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 10 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, and NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, R.sup.4a and R.sup.4b are selected, independently for each occurrence, from hydrogen, C1-C3 alkyl, halogen, NO.sub.2, CN, C1-C3 haloalkyl and C1-C3 alkoxy, R.sup.5a and R.sup.5b are independently selected from hydrogen, alkyl, cycloalkyl and phenyl, with the proviso that one of R.sup.5a and R.sup.5b must be hydrogen, R.sup.6 is selected from a C2-C5 alkanediyl, a C2-C5 alkenediyl and a C2-C5 alkynediyl group, wherein, in the alkanediyl, alkenediyl and alkynediyl group 1 or 2 carbon atoms may be replaced with a heteroatom selected from O and N, and wherein any hydrogen atom in the alkanediyl, alkenediyl and alkynediyl group may be replaced by a substituent R.sup.S11, wherein R.sup.S11 is selected, independently for each occurrence, from C1-C20 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 13 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, and NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, and/or two substituents R.sup.S11 may be linked to form, together with the atoms to which they are attached, a 5 to 14 membered carbocyclic or heterocyclic group which is optionally substituted by one or more further substituents; c) at least one anionic nucleophilic ligand L.sup.N which is coordinated as a further ligand to the rare earth metal cation; and d) optionally one or more neutral donor ligands L.sup.D coordinated as ligands to the rare earth metal cation.
2. The chelate complex in accordance with claim 1, wherein the rare earth metal cation is selected from Y.sup.3+, Yb.sup.3+, La.sup.3+ and Lu.sup.3+.
3. The chelate complex in accordance with claim 1, wherein R.sup.1a and R.sup.1b are independently selected from (i) to (iii) (i) a branched C6 to C15 alkyl group or a branched C6 to C15 alkoxy group comprising at least one of a tertiary and a quaternary carbon atom, which branched alkyl group and branched alkoxy group is optionally substituted, (ii) a group of the formula (S-1): ##STR00057## wherein R.sup.S1 is selected from a C1-C9 divalent alkyl group which is optionally substituted, O and a OC1-C8 divalent alkyl group which is optionally substituted, and R.sup.AR1 is selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted; (iii) a group of the formula (S-2) ##STR00058## wherein R.sup.S2 is selected from a C1-C6 trivalent alkyl group which is optionally substituted, O and a OC1-C5 trivalent alkyl group which is optionally substituted, and R.sup.AR2 and R.sup.AR3 are independently selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted.
4. The chelate complex in accordance with claim 1, wherein the anionic nucleophilic ligand L.sup.N is selected from a halogen ligand, a hydrocarbyl ligand, an -silylalkyl ligand, an amide ligand, a silylamide ligand, an alkoxide ligand, an aryloxide ligand, a borohydride (BH.sub.4.sup.) ligand, NO.sub.3.sup., a carboxylate ligand, a thiolate ligand, a sulfate ligand, and a sulfonate ligand.
5. The chelate complex in accordance with claim 1, which is a complex of the following formula (K1A) or (K1B): ##STR00059## wherein R.sup.1a, R.sup.1b, R.sup.2a, R.sup.2b, R.sup.3a, R.sup.3b, R.sup.4a, R.sup.4b, R.sup.5a, R.sup.5b and R.sup.6 are defined as in the preceding claims, M is a rare earth metal cation, L.sup.N is an anionic nucleophilic ligand, L.sup.S is a neutral donor ligand that is a neutral solvent ligand, and n is 0, 1 or 2; ##STR00060## wherein R.sup.1a, R.sup.1b, R.sup.2a, R.sup.2b, R.sup.3a, R.sup.3b, R.sup.4a, R.sup.4b and R.sup.6 are defined as in the preceding claims, M is a rare earth metal cation, L.sup.N is an anionic nucleophilic ligand L.sup.S is a neutral donor ligand that is a neutral solvent ligand, and n is 0, 1 or 2.
6. A process for the preparation of a chelate complex which comprises a step of reacting a rare earth metal precursor comprising a rare earth metal cation M with one of b1 or b2 b1) a pro-ligand of formula (PL1A) or a deprotonated form thereof from which the protons of the phenolic hydroxyl groups shown in formula (PL1A) are removed: ##STR00061## b2) a pro-ligand of formula (PL1B) or a deprotonated form thereof from which the protons of the phenolic hydroxyl groups shown in formula (PL1B) are removed: ##STR00062## wherein, in formulae (PL1A) and (PL1B), R.sup.1a and R.sup.1b independently represent a sterically demanding group comprising 6 or more skeleton atoms, and optionally, R.sup.1a and R.sup.1b may be linked to each other to provide a divalent organic residue, R.sup.2a and R.sup.2b are independently selected from hydrogen, C1-C20 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 10 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, a group of the formula (S-1) ##STR00063## wherein R.sup.S1 is selected from a C1-C9 divalent alkyl group which is optionally substituted, O and a OC1-C8 divalent alkyl group which is optionally substituted, and R.sup.AR1 is selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted, and a group of the formula (S-2) ##STR00064## wherein R.sup.S2 is selected from a C1-C6 trivalent alkyl group which is optionally substituted, O and a OC1-C5 trivalent alkyl group which is optionally substituted, and R.sup.AR2 and R.sup.AR3 are independently selected from a phenyl group which is optionally substituted and a 5- to 6-membered heteroaryl group which is optionally substituted, R.sup.3a and R.sup.3b are, independently for each occurrence, selected from hydrogen, C1-C10 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 10 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, and NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, R.sup.4a and R.sup.4b are selected, independently for each occurrence, from hydrogen, C1-C3 alkyl, halogen, NO.sub.2, CN, C1-C3 haloalkyl and C1-C3 alkoxy, R.sup.5a and R.sup.5b are independently selected from hydrogen, alkyl, cycloalkyl and phenyl, with the proviso that one of R.sup.5a and R.sup.5b must be hydrogen, R.sup.6 is selected from a C2-C5 alkanediyl, a C2-C5 alkenediyl and a C2-C5 alkynediyl group, wherein, in the alkanediyl, alkenediyl and alkynediyl group 1 or 2 carbon atoms may be replaced with a heteroatom selected from O and N, and wherein any hydrogen atom in the alkanediyl, alkenediyl and alkynediyl group may be replaced by a substituent R.sup.S11, wherein R.sup.S11 is selected, independently for each occurrence, from C1-C20 alkyl, halogen, NO.sub.2, CN, C1-C10 haloalkyl, C1-C10 alkoxy, aryloxy with a 6 to 10 membered aryl group which is optionally substituted, heteroaryloxy with a 5 to 10 membered heteroaryl group which is optionally substituted, C2-C5 alkenyl, C2-C5 alkynyl, a 6 to 13 membered aryl group which is optionally substituted, a 5 to 10 membered heteroaryl group which is optionally substituted, and NR.sup.S9R.sup.S10 where R.sup.S9 and R.sup.S10 are independently selected from C1-C5 alkyl, and/or two substituents R.sup.S11 may be linked to form, together with the atoms to which they are attached, a 5 to 14 membered carbocyclic or heterocyclic group which is optionally substituted by one or more further substituents; to form a chelate complex.
7. The process of claim 6, wherein the rare earth metal precursor comprising a rare earth metal cation M is a precursor complex of formula (PK1): ##STR00065## wherein M is a rare earth metal cation, p is an integer which corresponds to the valence of the cation M, q is 1 to 4, L.sup.N is an anionic nucleophilic ligand, and L.sup.D is a neutral donor ligand.
8. A process for the preparation of a polymer, comprising a step of contacting monomers comprising chiral cyclic ester monomers with a chelate complex in accordance with claim 1 to allow a polymerization reaction of the monomers to proceed.
9. The process for the preparation of a polymer in accordance with claim 8, which comprises a step of reacting, in a suitable solvent, a) a precursor complex of the rare earth metal cation of formula (PK1) ##STR00066## wherein M is a rare earth metal cation, p is an integer which corresponds to the valence of the cation M, q is 1 to 4, L.sup.N is an anionic nucleophilic ligand, and L.sup.D is a neutral donor ligand, with one of b1 or b2 b1) a pro-ligand of formula (PL1A) or a deprotonated form thereof from which the protons of the phenolic hydroxyl groups shown in formula (PL1A) are removed: ##STR00067## b2) a pro-ligand of formula (PL1B) or a deprotonated form thereof from which the protons of the phenolic hydroxyl groups shown in formula (PL1B) are removed: ##STR00068## wherein in formulae (PL1A) and (PL1B) R.sup.1a, R.sup.1b, R.sup.2a, R.sup.2b, R.sup.3a, R.sup.3b, R.sup.4a, R.sup.4b, R.sup.5a, R.sup.5b and R.sup.6 are defined as in claim 6, to form a chelate complex, and a step of contacting monomers comprising chiral cyclic ester monomers with the formed chelate complex without prior isolation of the chelate complex, to allow a polymerization reaction of the monomers to proceed.
10. The process in accordance with claim 6, wherein the rare earth metal cation M is selected from Y.sup.3+, Yb.sup.3+, La.sup.3+ and Lu.sup.3+.
11. The process for the preparation of a polymer in accordance with claim 8, wherein the monomers comprise chiral cyclic ester monomers of formula (M1), (M2) or (M3), or a mixture thereof: ##STR00069## wherein: R.sup.M1 to R.sup.M8 are independently selected from hydrogen and C1-C6 alkyl, with the proviso that R.sup.M1, R.sup.M2 and, if present, R.sup.M3 and R.sup.M4 in formula (M1) are selected such that the monomer of formula (M1) contains at least one chiral carbon atom, that R.sup.M5 and R.sup.M6 in formula (M2) are selected such that the monomer of formula (M2) contains at least one chiral carbon atom and R.sup.M7 and R.sup.M8 in formula (M3) are selected such that the monomer of formula (M3) contains at least one chiral carbon atom, and the variables is 1, 2, 3 or 4.
12. The process for the preparation of a polymer in accordance with claim 8, wherein the monomers comprise racemic -butyrolactone.
13. The process for the preparation of a polymer in accordance with claim 8, wherein the polymer is poly(3-hydroxybutyrate).
14. (canceled)
15. Poly(3-hydroxybutyrate), having an isotacticity P.sub.m in the range of 0.78 to 0.92, a number average molecular weight M.sub.n of 12 kg mol.sup.1 or more, and a polydispersity index PDI of 1.5-3.5.
16. The process of claim 7, wherein L.sup.D is a solvent ligand L.sup.S.
17. The process of claim 9, wherein L.sup.D is a solvent ligand L.sup.S.
18. A process for the preparation of a polymer, comprising a step of contacting monomers comprising chiral cyclic ester monomers with a chelate complex obtainable by the process in accordance with claim 6 to allow a polymerization reaction of the monomers to proceed.
19. The process for the preparation of a polymer in accordance with claim 18, wherein the monomers comprise chiral cyclic ester monomers of formula (M1), (M2) or (M3), or a mixture thereof: ##STR00070## ##STR00071## wherein: R.sup.M1 to R.sup.M8 are independently selected from hydrogen and C1-C6 alkyl, with the proviso that R.sup.M1, R.sup.M2 and, if present, R.sup.M3 and R.sup.M4 in formula (M1) are selected such that the monomer of formula (M1) contains at least one chiral carbon atom, that R.sup.M5 and R.sup.M6 in formula (M2) are selected such that the monomer of formula (M2) contains at least one chiral carbon atom and R.sup.M7 and R.sup.M8 in formula (M3) are selected such that the monomer of formula (M3) contains at least one chiral carbon atom, and the variables is 1, 2, 3 or 4.
20. The process for the preparation of a polymer in accordance with claim 18, wherein the monomers comprise racemic -butyrolactone.
21. The process for the preparation of a polymer in accordance with claim 18, wherein the polymer is poly(3-hydroxybutyrate).
Description
EXAMPLES
Materials and Methods
[0334] All manipulations containing air- and/or moisture sensitive compounds were carried out under argon atmosphere using standard Schlenk or glovebox techniques. Glassware was flame-dried under vacuum prior to use. Unless otherwise stated, all chemicals were purchased from Sigma-Aldrich, TCI Chemicals or ABCR and used as received. Solvents were obtained from an MBraun MB-SPS 800 solvent purification system and stored over 3 molecular sieves prior to use. Rac-BBL was dried over CaH.sub.2 and distilled prior to use. Y[N(SiHMe.sub.2).sub.2].sub.3(THF).sub.2,.sup.57 La[N(SiHMe.sub.2).sub.2].sub.3(THF).sub.2,.sup.57 and Schiff base precursors L1 and L2 were prepared according to literature procedures..sup.43 Schiff base precursors L3 and L4 were prepared according to literature procedures but 3-trityl-5-tert-butylsalicylaldehyde was used instead of 3-trityl-5-methylsalicylaldehyde, and 3,5-dicumylsalicylaldehyde was used instead of 3,5-bis(tert-butyl)salicylaldehyde, respectively..sup.43
[0335] Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AV-III-500 spectrometer equipped with a QNP-Cryoprobe or AV-III-400 spectrometers at ambient temperature (298 K). .sup.1H and .sup.13C{.sup.1H}NMR spectroscopic chemical shifts are reported in ppm relative to tetramethylsilane and were referenced internally to the relevant residual solvent resonances. The following abbreviations are used: br, broad; s, singlet; d, doublet; t, triplet; p, pentet; m, multiplet; AB, AB system. The tacticity of PHB was determined by integration of the carbonyl region of the .sup.13C{.sup.1H}NMR spectrum..sup.26
[0336] Elemental analyses were measured with a EURO EA instrument from HEKAtech at the Laboratory for Microanalysis, Catalysis Research Center, Technical University of Munich. Liquid Injection Field Desorption Ionization Mass Spectrometry (LIFDI-MS) was measured directly from an inert atmosphere glovebox with a Thermo Fisher Scientific Exactive Plus Orbitrap equipped with an ion source from Linden CMS.
[0337] Polymer weight-average molecular weight (M.sub.w), number-average molecular weight (M.sub.n) and polydispersity indices (=M.sub.w/M.sub.n) were determined via gel permeation chromatography (GPC) relative to polystyrene standards on a PL-SEC 50 Plus instrument from Polymer Laboratories. The analysis was performed at ambient temperatures using chloroform as the eluent at a flow rate of 1.0 mL min.sup.1.
Ligands
[0338] The following formulae illustrate the structures of pro-ligands and metal precursor compounds used for the preparation of chelate complexes in accordance with the invention
##STR00048## ##STR00049##
[0339] The following formulae illustrate the structures of pro-ligands used for the preparation of chelate complexes used as reference complexes and/or as synthetic intermediates.
##STR00050##
Synthesis of Salan Pro-Ligands L1-L7
##STR00051##
[0340] The synthesis of salan pro-ligands L1-L7 followed a similar synthetic procedure and therefore the synthesis is described as a general procedure. Using racemic or enantiopure Schiff base precursors L1-L3 or L7, racemic or enantiopure salan pro-ligands are obtained in the case of L1-L3 or L7, respectively. The synthesis of L1 and L3 has previously been described in literature..sup.51, 58 Schiff base precursor L5 was prepared following an adopted literature procedure..sup.43 3,5-Dicumylsalicylaldehyde (7.0 mmol, 2.0 eq.) was dissolved in 65 mL of ethanol, and ethylenediamine (3.5 mmol, 1.0 eq.) and 0.1 mL of formic acid was added. The mixture was refluxed for 45 min. Subsequently, the reaction mixture was cooled to room temperature, the precipitate filtered and washed with pentane. Yield: 81%, yellow solid.
[0341] Schiff base precursor L6 was prepared according to the following procedure. 3,5-Dicumylsalicylaldehyde (10.0 mmol, 2.0 eq.) was suspended in 25 mL of methanol and 1,3-diaminopropane (5.0 mmol, 1.0 eq.) was added. The mixture was refluxed overnight. Subsequently, the reaction mixture was cooled to room temperature, the precipitate filtered and washed with methanol. Yield: 80%, yellow solid.
[0342] Schiff base precursor L7 was prepared according to the following procedure. 5-(tert-butyl)-3-(1,1-diphenylethyl)-2-hydroxybenzaldehyde (8.0 mmol, 2.0 eq.) was suspended in 100 mL of methanol, and ()-trans-1,2-diaminocyclohexane (4.0 mmol, 1.0 eq.) and 0.1 mL of formic acid was added. The mixture was refluxed for 5 h. Subsequently, the reaction mixture was cooled to room temperature, the precipitate filtered and washed with methanol. Yield: 81%, yellow solid.
[0343] General procedure for L1-L7. The bis-imine type precursor (salen-type pro-ligand) (6.0 mmol, 1 eq.) was dissolved in 25 mL of tetrahydrofuran and 25 mL of methanol. The reaction mixture was cooled to 0 C. and sodium borohydride, NaBH.sub.4 (60.0 mmol, 10 eq.) was added portionwise. Subsequently, the reaction mixture was allowed to warm to room temperature and stirred for 3 h at this temperature. The solvent was removed under reduced pressure, the residue dissolved in dichloromethane (250 mL) and water (125 mL) was added.
[0344] The phases were separated, and the organic layer washed with water (275 mL) and brine (175 mL). The organic layer was dried over Na.sub.2SO.sub.4, the solvent removed under reduced pressure and the residue further purified as described below.
[0345] Salan pro-ligand L1: The residue was recrystallized from methanol/dichloromethane. Yield: 80%, colorless solid.
[0346] .sup.1H NMR (400 MHz, CDCl.sub.3): 10.64 (br s, 2H, OH), 7.21 (d, J=2.5 Hz, 2H, ArH), 6.86 (d, J=2.5 Hz, 2H, ArH), 3.97 (AB, J=13.4 Hz, 4H, NCH.sub.2), 2.51-2.43 (m, 2H, Cy), 2.23-2.13 (m, 2H, Cy), 1.76-1.68 (m, 2H, Cy), 1.38 (s, 18H, .sup.tBu), 1.28 (s, 18H, .sup.tBu), 1.27-1.21 (m, 4H, Cy). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 154.5, 140.8, 136.1, 123.3, 123.2, 122.5, 60.1, 51.0, 35.0, 34.3, 31.8, 30.9, 29.8, 24.3. Anal. Calc. for C.sub.36H.sub.58N.sub.2O.sub.2: C, 78.49; H, 10.61; N, 5.09. Found: C, 77.43; H, 10.33; N, 5.06%.
[0347] Salan pro-ligand L2: The residue was washed with methanol. Yield: 86%, colorless solid. .sup.1H NMR (400 MHz, CDCl.sub.3): 10.38 (br s, 2H, OH), 7.31-7.23 (m, 10H, ArH), 7.20-7.08 (m, 10H, ArH), 7.05-6.99 (m, 2H, ArH), 6.64 (d, J=2.5 Hz, 2H, ArH), 3.64 (AB, J=13.5 Hz, 4H, NCH.sub.2), 1.87-1.79 (m, 2H, Cy), 1.71 (s, 6H, CMe.sub.2Ph), 1.69 (s, 12H, CMe.sub.2Ph), 1.68-1.63 (m, 2H, Cy), 1.57 (s, 6H, CMe.sub.2Ph), 1.55-1.50 (m, 2H, Cy), 0.98-0.83 (m, 2H, Cy), 0.71-0.51 (m, 4H, Cy and NH). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 154.0, 152.1, 151.7, 139.8, 135.4, 128.0, 127.6, 126.9, 125.9, 125.7, 125.5, 124.6, 124.3, 122.1, 58.0, 49.3, 42.6, 42.0, 31.3, 31.2, 30.9, 30.1, 28.0, 24.6. Anal. Calc. for C.sub.56H.sub.66N.sub.2O.sub.2: C, 84.17; H, 8.32; N, 3.51. Found: C, 83.89; H, 8.45; N, 3.55%.
[0348] Salan pro-ligand L3: The residue was washed with methanol. Yield: 74%, colorless solid.
[0349] .sup.1H NMR (400 MHz, CDCl.sub.3): 10.30 (br s, 2H, OH), 7.23-7.08 (m, 30H, ArH), 7.05 (d, J=2.5 Hz, 2H, ArH), 6.83 (d, J=2.6 Hz, 2H, ArH), 3.72 (AB, J=13.8 Hz, 4H, NCH.sub.2), 1.83-1.73 (m, 2H, Cy), 1.56-1.44 (m, 4H, Cy), 1.13 (s, 18H, .sup.tBu), 0.89-0.78 (m, 2H, Cy), 0.63-0.43 (m, 4H, Cy and NH). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 154.1, 146.3, 140.1, 133.3, 131.4, 127.5, 127.0, 125.5, 124.3, 121.9, 63.5, 57.9, 49.3, 34.2, 31.7, 29.9, 24.7. Anal. Calc. for C.sub.66H.sub.70N.sub.2O.sub.2: C, 85.86; H, 7.64; N, 3.03. Found: C, 85.74; H, 7.80; N, 3.16%.
[0350] Salan pro-ligand L4: L4 was prepared according to the general procedure but the stirring time of the reaction mixture was 4 h at room temperature. The residue was washed with methanol. Yield: 84%, yellow solid.
[0351] .sup.1H NMR (400 MHz, CDCl.sub.3): 7.31-7.27 (m, 10H, ArH), 7.23-7.15 (m, 10H, ArH), 7.14-7.08 (m, 2H, ArH), 6.95 (br s, 2H, OH), 6.92 (d, J=2.4 Hz, 2H, ArH), 6.80-6.75 (m, 2H, ArH), 6.70-6.64 (m, 2H, ArH), 4.11 (s, 4H, NCH.sub.2), 3.40 (br s, 2H, NH), 1.71 (s, 12H, CMe.sub.2Ph), 1.62 (s, 12H, CMe.sub.2Ph). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 152.1, 151.2, 150.4, 141.7, 136.9, 135.5, 128.4, 128.1, 126.9, 126.5, 125.8, 125.8, 125.7, 125.2, 123.8, 121.0, 114.0, 47.6, 42.7, 42.2, 31.2, 29.8. Anal. Calc. for C.sub.56H.sub.60N.sub.2O.sub.2: C, 84.81; H, 7.63; N, 3.53. Found: C, 84.76; H, 7.82; N, 3.37%.
[0352] Salan pro-ligand L5: The residue was washed with methanol. Yield: 69%, off-white solid.
[0353] .sup.1H NMR (400 MHz, CDCl.sub.3): 10.37 (br s, 2H, OH), 7.33-7.27 (m, 8H, ArH), 7.24 (d, J=2.6 Hz, 2H, ArH), 7.21-7.14 (m, 10H, ArH), 7.11-7.04 (m, 2H, ArH), 6.70 (d, J=2.5 Hz, 2H, ArH), 3.71 (s, 4H, ArCH.sub.2), 2.43 (s, 4H, NCH.sub.2), 1.70 (s, 12H, CMe.sub.2Ph), 1.65 (s, 12H, CMe.sub.2Ph). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 154.0, 151.7, 151.5, 140.0, 135.4, 128.0, 127.7, 126.9, 125.8, 125.6, 125.5, 124.9, 124.9, 121.9, 53.1, 47.6, 42.6, 42.1, 31.2, 29.6.
[0354] Salan pro-ligand L6: The residue was recrystallized from methanol. Yield: 51%, colorless solid.
[0355] .sup.1H NMR (400 MHz, CDCl.sub.3): 7.29-7.26 (m, 8H, ArH), 7.22 (d, J=2.5 Hz, 2H, ArH), 7.20-7.14 (m, 10H, ArH), 7.10-7.04 (m, 2H, ArH), 6.70 (d, J=2.5 Hz, 2H, ArH), 3.72 (s, 4H, ArCH.sub.2), 2.40 (t, J=6.8 Hz, 4H, NCH.sub.2CH.sub.2CH.sub.2N), 1.68 (s, 12H, CMe.sub.2Ph), 1.63 (s, 12H, CMe.sub.2Ph), 1.39 (p, J=7.0 Hz, 2H, NCH.sub.2CH.sub.2CH.sub.2N). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 154.2, 151.6, 151.5, 140.0, 135.4, 128.0, 127.8, 126.9, 125.8, 125.6, 125.4, 125.0, 124.9, 122.2, 53.3, 46.5, 42.6, 42.2, 31.2, 29.7, 29.5. Anal. Calc. for C.sub.53H.sub.62N.sub.2O.sub.2: C, 83.86; H, 8.23; N, 3.69. Found: C, 83.84; H, 8.21; N, 3.70%.
[0356] Salan pro-ligand L7: The residue was washed with methanol. Yield: 62%, off-white solid.
[0357] .sup.1H NMR (400 MHz, CDCl.sub.3): 7.27-7.10 (m, 20H, ArH), 6.84 (d, J=2.5 Hz, 2H, ArH), 6.56 (d, J=2.5 Hz, 2H, ArH), 3.84 (AB, J=13.8 Hz, 4H, NCH.sub.2), 2.28 (s, 6H, CMePh.sub.2), 2.12-1.97 (m, 4H, Cy), 1.68-1.57 (m, 2H, Cy), 1.18-1.03 (m, 2H, Cy), 1.11 (s, 18H, .sup.tBu), 0.99-0.85 (m, 2H, Cy). .sup.13C{1H}NMR (101 MHz, CDCl.sub.3): 154.0, 149.1, 149.0, 140.2, 135.0, 128.7, 128.6, 127.7, 127.7, 127.1, 125.7, 125.6, 123.8, 122.3, 59.4, 52.0, 50.3, 34.1, 31.6, 30.8, 27.8, 24.5.
Synthesis of Salalen Pro-Ligand L8
##STR00052##
[0358] Precursor L8 was prepared following an adapted literature procedure (Catal. Sci. Technol., 2014, 4, 3964). Ethylenediamine (5.6 mmol, 1.0 eq.) was dissolved in 40 mL of methanol and 3,5-dicumylsalicylaldehyde (5.6 mmol, 1.0 eq.) dissolved in 50 mL of methanol/THF (4:1) was added dropwise. The resulting suspension was stirred for 20 h at room temperature and afterwards cooled to 0 C. Sodium borohydride, NaBH.sub.4 (55.8 mmol, 10 eq.) was added portionwise, and then stirred for 2 h. Subsequently, the reaction mixture was allowed to warm to room temperature and stirred overnight at this temperature. The solvent was removed under reduced pressure, the residue dissolved in dichloromethane (250 mL) and water (125 mL) was added. The phases were separated, and the organic layer washed with water (275 mL) and brine (175 mL). The organic layer was dried over Na.sub.2SO.sub.4, the solvent removed under reduced pressure and the residue recrystallized from methanol. The crystalized white solid was found to be the side product L5 while the filtrate contained, after removal of the solvent the targeted precursor L8 with good purity. Yield: 47%, colorless solid.
[0359] .sup.1H NMR (400 MHz, CDCl.sub.3): 7.32-7.15 (m, 11H, ArH), 6.72 (d, J=2.5 Hz, 1H, ArH), 3.81 (s, 2H, HNCH.sub.2), 2.71-2.64 (m, 2H, HNCH.sub.2), 2.57-2.00 (m, 2H, H.sub.2NCH.sub.2), 1.67 (s, 6H, CMe.sub.2Ph), 1.64 (s, 6H, CMe.sub.2Ph).
[0360] Salalen pro-ligand L8: The half-salan type precursor L8 (2.75 mmol, 1.0 eq.) was dissolved in 40 mL of methanol and 3,5-dicumylsalicylaldehyde (2.75 mmol, 1.0 eq.) dissolved in 20 mL of methanol was added at room temperature and stirred for 24 h. Subsequently, the precipitate was filtered and washed with methanol. The residue was recrystallized from methanol/dichloromethane. Yield: 71%, yellow solid.
[0361] .sup.1H NMR (400 MHz, CDCl.sub.3): 13.99 (br s, 1H, OH), 10.46 (br s, 1H, OH), 8.10 (s, 1H, NCH), 7.35 (d, J=2.4 Hz, 1H, ArH), 7.32-7.05 (m, 21H, ArH), 6.99 (d, J=2.4 Hz, 1H, ArH), 6.71 (d, J=2.4 Hz, 1H, ArH), 3.77 (s, 2H, NHCH.sub.2), 3.42 (t, J=5.8 Hz, 2H, NCH.sub.2), 2.72 (t, J=5.8 Hz, 2H, HNCH.sub.2), 1.71 (s, 6H, CMe.sub.2Ph), 1.67 (s, 6H, CMe.sub.2Ph), 1.65 (s, 6H, CMe.sub.2Ph), 1.63 (s, 6H, CMe.sub.2Ph). .sup.13C{.sup.1H}NMR (101 MHz, CDCl.sub.3): 167.5, 157.6, 153.9, 151.5, 151.4, 150.8, 150.7, 140.2, 140.0, 136.2, 135.5, 129.3, 128.2, 128.1, 128.0, 127.9, 127.8, 126.9, 126.8, 125.8, 125.7, 125.7, 125.6, 125.5, 125.2, 125.1, 125.0, 121.9, 118.0, 58.9, 52.6, 47.9, 42.5, 42.5, 42.1, 42.0, 31.1, 30.9, 29.6, 29.5. Anal. Calc. for C.sub.52H.sub.58N.sub.2O.sub.2: C, 84.06; H, 7.87; N, 3.77. Found: C, 83.97; H, 8.07; N, 3.76%.
Example 1: Synthesis of Salan Catalyst 1
##STR00053##
[0362] To a solution of Y[N(SiHMe.sub.2).sub.2].sub.3(THF).sub.2 (126 mg, 200 mol, 1 eq.) in 5 mL of toluene, a solution of L2 in 5 mL of toluene was added. The reaction mixture was stirred for 2 h at room temperature. The solvent was removed to afford 1 as an off-white solid.
[0363] LIFDI-MS: [(L2)Y].sup.+ (m/z 885.40, calc. 885.40), [(L2)Y(N(SiHMe.sub.2).sub.2)].sup.+ (m/z 1017.46, calc. 1017.47).
Example 2: General Polymerization Procedure Using In Situ Formed Catalysts
[0364] In an inert atmosphere glovebox, a 20 mL glass reactor was charged with a predetermined amount of Y[N(SiHMe.sub.2).sub.2].sub.3(THF).sub.2 (1 eq.) and salan or salalen pro-ligand (1 eq.) such as L1-L8. The respective amount of toluene was added such that the overall monomer concentration after rac-BBL addition is 2.0M. The reaction mixture was stirred for 1 h at room temperature and then, rac-BBL (equivalents as specified in the polymerization table) was added to this mixture. After stirring for a desired time period at room temperature, the polymerization was quenched by the addition of 0.5 mL of methanol. An aliquot sample was taken for determination of conversion by .sup.1H NMR spectroscopy. The quenched mixture was then precipitated into 20 mL of diethyl ether/pentane (1/1), filtered, washed with diethyl ether/pentane (1/1) and dried in vacuo.
[0365]
[0366]
[0367]
[0368]
Example 3: Polymerization Procedure Using Isolated Catalyst
[0369] In an inert atmosphere glovebox, a 5 mL glass reactor was charged with catalyst 1 (18.6 mg, 18.3 mol, 1 eq.) as prepared in Example 2 and 1.53 mL of toluene was added. The mixture was stirred for 5 min at room temperature and then, the polymerization was initiated by rapid addition of rac-BBL (315.0 mg, 3.7 mmol, 200 eq.). After stirring for a desired time period at room temperature, the polymerization was quenched by the addition of 0.5 mL of methanol. An aliquot sample was taken for determination of conversion by .sup.1H NMR spectroscopy. The quenched mixture was then precipitated into 10 mL of diethyl ether/pentane (1/1), filtered, washed with diethyl ether/pentane (1/1) and dried in vacuo.
Example 4: Polymerization Procedure Using In Situ Formed Catalysts and Benzyl Alcohol as Initiator
[0370] In an inert atmosphere glovebox, a 5 mL glass reactor was charged with a predetermined amount of Y[N(SiHMe.sub.2).sub.2].sub.3(THF).sub.2 (5.8 mg, 9.2 mol, 1 eq.) and salan pro-ligand L2 (7.3 mg, 9.2 mol, 1 eq.). The respective amount of toluene was added such that the overall monomer concentration after rac-BBL addition is 2.0M. The reaction mixture was stirred for 1 h at room temperature and then, a predetermined amount of a BnOH stock solution in toluene was added (eq. of BnOH as specified in the polymerization table) and the mixture stirred for an additional 5 min at room temperature. The polymerization was initiated by rapid addition of rac-BBL (315.0 mg, 3.7 mmol, 400 eq.). After stirring for a desired time period at room temperature, the polymerization was quenched by the addition of 0.5 mL of methanol. An aliquot sample was taken for determination of conversion by .sup.1H NMR spectroscopy. The quenched mixture was then precipitated into 10 mL of diethyl ether/pentane (1/1), filtered, washed with diethyl ether/pentane (1/1) and dried in vacuo.
Results of Polymerization Examples Using Salan Catalysts
[0371] The following table 1 summarizes the polymerization examples using the chelate complexes of the invention and their results.
TABLE-US-00001 TABLE 1 Polymerization data for ROP of rac-BBL using the process described above..sup.a T M.sub.n .sup.c catalytic [MM]/ ( t conv..sup.b (kg/ entry system [L + Y] C.) (min) (%) mol) .sup.c P.sub.m .sup.d 1 L2 + Y 200 rt. 1 98 41 2.2 0.82 2 L2 + Y 400 rt. 2 99 85 2.0 0.83 3 L2 + Y 2000 rt. 3 80 290 2.0 0.84 4 L2 + Y 3000 rt. 10 85 445 1.8 0.75 5 L2 + Y 4000 rt. 60 88 565 1.7 0.71 6 L2 + Y 200 35 60 >99 130 3.2 0.89 7.sup.e L2 + Y 400 rt. 1 99 60 1.9 0.75 8.sup.f L2 + Y 400 rt. 30 100 12 1.1 0.62 9 L3 + Y 200 rt. 3 99 43 3.5 0.09 10 L4 + Y 200 rt. 30 52 103 1.8 0.82 11 L5 + Y 200 rt. 3 91 77 2.1 0.85 12 L6 + Y 200 rt. 3 55 184 1.9 0.88 13 L2 + La 200 rt. 30 32 n.d. n.d. 0.61 14 L2 + Lu 200 rt. 1 97 67 1.8 0.82 15.sup.g L2 + Y 200 rt. 1 97 45 1.8 0.81 (1) 16 L7 + Y 200 rt. 1 99 47 1.9 0.83 .sup.aCatalyst was prepared in situ by treatment of Y(bdsa).sub.3(THF).sub.2 (Y), La(bdsa).sub.3(THF).sub.2 (La) or Lu(bdsa).sub.3(THF).sub.2 (Lu) with salan pro-ligand L (1 eq.) in toluene at room temperature (rt.) for 1 h prior to addition of monomer (MM), [MM]/[L + Y] indicates the molar ratio of monomer to the complex formed in situ from Y (or La, Lu) and L (Protocol Example 2). [BBL] = 2.0M. .sup.bConversion determined by .sup.1H NMR spectroscopy. .sup.c Molecular weight and dispersity of polymer determined by GPC in CHCl.sub.3 at rt. relative to polystyrene standards. .sup.d Tacticity determined by .sup.13C NMR spectroscopy, integration of the carbonyl signal. .sup.e1 eq. of BnOH added prior to monomer addition. .sup.f5 eq. of BnOH added prior to monomer addition. .sup.gIsolated catalyst used for polymerization run (Example 3). n.d. = not determined.
[0372] Using L2 and metal precursor Y(bdsa).sub.3(THF).sub.2 (Y, bdsa=bis(dimethylsilyl)amide) in the in situ protocol (Example 2), iso-enriched PHB with P.sub.m=0.82 was obtained (Table 1, entry 1). The activity of catalyst system L2+Y was also further improved (TOF up to 32 000 h.sup.1). Gradually increasing the [M]/[L2+Y] ratio up to 4000/1 was feasible and iso-enriched PHB with very high molecular weight could be obtained (Table 1, entries 2-5). Decreasing the polymerization temperature to 35 C. increased the stereoselectivity of the process and PHB with a P.sub.m=0.89 was isolated (Table 1, entry 6). Addition of various equivalents of benzyl alcohol (BnOH) to the in situ formed catalyst species prior to monomer addition gave PHB with reduced isotacticity with increasing amount of BnOH equivalents (Table 1, entries 7 and 8). Thus, control over the degree of isotacticity is also feasible using additives such as alcohols in this catalyst/polymerization system. Switching the ortho-substituent of the pro-ligand to a sterically more demanding trityl group (CPh.sub.3, L3), the stereocontrol in ROP of rac-BBL with L3+Y switched to high syndioselectivity (P.sub.r=0.91; Table 1, entry 9). Highly iso-enriched PHB could also be accessed by catalyst systems consisting of L4+Y, L5+Y or L6+Y (Table 1, entries 10-12), showing that the use of a chiral backbone is not necessary for achieving high stereocontrol. The approach described herein could also be extended to the use of different metal precursors. For example, using L2 and a lanthanum precursor such as La(bdsa).sub.3(THF).sub.2 (La), iso-enriched PHB was accessible (P.sub.m=0.61; Table 1, entry 13). Regarding the ROP of rac-BBL using isolated salan-type catalysts (Protocol Example 3), virtually identical polymerization outcomes were observed compared to the ones using the protocol of Example 2 (Table 1, entry 15).
[0373] Catalyst system L2+Y shows the highest activity for the isoselective production of PHB reported to date. Additionally, the achieved isoselectivity of P.sub.m=0.89 at a reaction temperature of 35 C. is the highest reported to date for the ROP of rac-BBL. It is worth noting here, that the yttrium salen-based catalyst system reported by Chen et al. showing very high isoselectivity in the ROP of the eight-membered diolide was not able to induce stereocontrol in the ROP of rac-BBL..sup.43 This highlights the importance of the presence of an amine moiety in the ligand/catalyst structure.
[0374] The following table 2 summarizes the polymerization examples using reference chelate complexes for comparative purposes.
TABLE-US-00002 TABLE 2 Polymerization data for ROP of rac-BBL. T M.sub.n .sup.c catalytic [MM]/ ( t conv..sup.b (kg/ entry system [L + Y] C.) (min) (%) mol) .sup.c P.sub.m .sup.d 1 L1 + Y 200 rt. 120 83 35 1.9 0.63 2 X1 + Y 200 rt. 15 59 23 1.5 0.63 3 X2 + Y 200 rt. 30 76 24 1.4 0.67 4 L1 + Y 200 rt. 1440 22 8 1.9 0.50 5 L2 + Y 200 rt. 1440 20 9 1.8 0.51 6 L3 + Y 200 rt. 1440 8 n.d. n.d. 0.55 7 L4 + Y 200 rt. 1440 2 n.d. n.d. n.d. .sup.aCatalyst was prepared in situ by treatment of Y(bdsa).sub.3(THF).sub.2 (Y) with salan or salen pro-ligand X or L (1 eq.) in toluene at room temperature (rt.) for 1 h prior to addition of monomer (Protocol Example 2). [BBL] = 2.0M. .sup.bConversion determined by .sup.1H NMR spectroscopy. .sup.c Molecular weight and dispersity of polymer determined by GPC in THF at 40 C. relative to polystyrene standards. .sup.d Tacticity determined by .sup.13C NMR spectroscopy, integration of the carbonyl signal. n.d. = not determined.
Polymerization Results Using In Situ Prepared Salalen Catalyst
TABLE-US-00003 TABLE 3 Polymerization data for ROP of rac-BBL. catalytic [MM]/ T t conv..sup.b M.sub.n .sup.c entry system [L + Y] ( C.) (min) (%) (kg/mol) .sup.c P.sub.m .sup.d 1 L8 + Y 200 rt. 15 60 49 1.7 0.92 .sup.aCatalyst was prepared in situ by treatment of Y(bdsa).sub.3(THF).sub.2 (Y) with salalen pro-ligand L8 (1 eq.) in toluene at room temperature (rt.) for 1 h prior to addition of monomer (MM), [MM]/[L8 + Y] indicates the molar ratio of monomer to the complex formed in situ from Y and L8 (Protocol Example 2). [BBL] = 2.0M. .sup.bConversion determined by .sup.1H NMR spectroscopy. .sup.c Molecular weight and dispersity of polymer determined by GPC in CHCl.sub.3 at rt. relative to polystyrene standards. .sup.d Tacticity determined by .sup.13C NMR spectroscopy, integration of the carbonyl signal.
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