Reduction by a silane in the presence of Zinc catalyst
The present invention relates to the field of organic synthesis. More specifically, it concerns a process for the selective reduction of a C 3 -C 70 substrate containing one or more carbonyl or carboxylic functional groups into the corresponding alcohol diol, or polyalcohol in the presence of a silane and at least one catalyst or pre-catalyst in the form of a zinc complex. The Zinc complex of formula (I) or (II) is also part of the invention.
1 . Process for the reduction of a C 3 -C 70 substrate containing one or more carbonyl or carboxylic functional groups into the corresponding alcohol, diol, or polyalcohol, the process comprising
a) reacting the C 3 -C 70 substrate containing one or more carbonyl or carboxylic functional groups with a silane and at least one catalyst or pre-catalyst in the form of a zinc complex of formula
wherein X is an anion and L is an aminoalcohol or thioalcohol, wherein all ligands X are identical or different and all ligands L are identical or different; and L′ is of formula (III);
wherein m represents an integer between 0 and 1000, n represent an integer between 0 and 1000, G represents C 1-6 hydrocarbon group, optionally comprising one or two oxygen atoms and/or one or two nitrogen atoms, Z represents a nitrogen or a sulphur atom, R 1 and R 2 are, independently from each other, a hydrogen atom or a C 1-3 alkyl group, o is 0 when Z is a sulphur atom or o is 1 when Z is a nitrogen atom; and
b) hydrolyzing the obtained siloxane with a basic agent to form an alcohol, a diol or a polyalcohol.
2 . The process according to claim 1 , wherein the silane is polymethylhydrosiloxane (PMHS).
3 . The process according to claim 2 , wherein the zinc complex of formula (II) is formed in situ by the reaction between PMHS and zinc complex of formula (I) prior to adding the substrate.
4 . The process according to claim 1 , wherein X is an anion selected from the group consisting of carboxylate, β-diketonate, enolate, amide, silylamide, alkyl, cycloalkyl, alkoxy, aryl, aryloxy, alkoxyalkyl, alkoxyaryl, aralkoxy, aralcoyl and alkylaryl groups having from 1 to 20 carbon atoms, halide, carbonate and cyanide.
5 . The process according to claim 1 , wherein X is selected from the group consisting of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, diethylacetate, benzoate, 2-ethylhexanoate, naphthenate and stearate.
6 . The process according to claim 1 , wherein said ligand L is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, diethylaminoethanol, dimethylaminomethanol, diethylaminomethanol, 2-aminobutanol, ephedrine, prolinol, valinol, 2-(Diisopropylamino) ethanol, 2-{[2-(Dimethylamino)ethyl] methylamino} ethanol, 1,3-Bis(dimethylamino)-2-propanol, 2-[2-(Dimethylamino) ethoxy] ethanol, 1-Dimethylamino-2-propanol, cinchonidine, quinine and quinidine.
7 . The process according to claim 1 , wherein the substrate is a compound of formula (IV):
wherein p is 0 or 1, R a represents a linear, branched or cyclic C 1 -C 30 aromatic, alkyl or alkenyl group, optionally substituted and R b represents a hydrogen atom, a linear, branched or cyclic C 1 -C 30 aromatic, alkyl or alkenyl group, optionally substituted; or
R a and R b are bonded together and form a C 4 -C 20 saturated or unsaturated group, optionally substituted; and
wherein the substituents of R a and R b are one, two or three halogen, OR c , NR c 2 or R c groups, in which R c is a hydrogen atom, a halogenated C 1 -C 2 group or a C 1 to C 10 cyclic, linear or branched alkyl, or alkenyl group.
8 . The process according to claim 1 , wherein the substrate is a linear or branched, aliphatic or cyclic, saturated or unsaturated ketone or aldehyde selected from the group consisting of butanal, pentanal, hexanal, trans-hex-2-en-1-al, heptanal, octanal, decanal, dodecanal, acroleine, methacroleine, crotonaldehyde, prenal, citral, retinal, campholenic aldehyde, cinnamic aldehyde, hexylcinnamic aldehyde, formylpinane, nopal, benzaldehyde, cuminic aldehyde, vanillin, salicylic aldehyde, hexan-2-one, octan-2-one, nonan-4-one, dodecan-2-one, methyl vinyl ketone, mesityl oxide, acetophenone, cyclopentanone, cyclohexanone, cyclododecanone, cyclohex-1-en-3-one, isophorone, oxophorone, carvone, camphor, beta-ionone, geranylacetone, 3-methyl-cyclopenta-1,5-dione, 3,3-dimethyl-5-(2,2,3-trimethyl-cyclopent-3-en-1-yl)-pent-4-en-2-one and 2-pentylcyclopenten-2-one.
9 . The process according to claim 1 , wherein the substrate is an ester or lactone selected from the group consisting of alkyl and aryl acetates, propionates, butyrates, isobutyrates, benzoates, acrylates, crotonates, cinnamates, cis-3-hexenoates, sorbates, salicylates, 10-undecylenates, oleates and linoleates, fatty esters of natural or synthetic origin, caprolactone, butyrolactone, dodecalactone, diketene and sclareolide.
10 . The process according to claim 1 , wherein said substrate is carboxylic acid selected from the group consisting of 4-methyl-6-(2,6,6-trimethylcyclohex-1-en-1-yl) hex-3-enoic acid, benzoic acid, butanoic acid, pentanoic acid and C 1 -30 alkyl acid or aryl acid.
11 . Process according to claim 1 , wherein the substrate is an animal or vegetable fat.
12 . Process according to claim 11 , wherein the substrate is a triglyceride of a fatty acid of formula (V):
in which R d , R e and R f are hydrocarbon groups which are identical or different, linear or branched, saturated or unsaturated, and which can contain from 1 to 20 carbon atoms.
13 . Process according to claim 11 , wherein said animal or vegetable fat is at least one oil selected from the group consisting of trioleine, peanut oil, sunflower oil, soya oil, olive oil, colza oil, sesame oil, grapeseed oil, linseed oil, cacao butter, cotton oil, copra oil, coconut oil, palm oil, jojoba oil, palm kernel oil, whale sperm oil, and pork, beef, mutton, or chicken fat.
14 . The process according to claim 1 , wherein the basic agent used for the hydrolysis is sodium or potassium hydroxide, lime or sodium carbonate.
15 . A zinc complex of formula
wherein X is an anion and L is an aminoalcohol or thioalcohol, wherein all ligands X are identical or different and all ligands L are identical or different; and L′ is of formula (III):
wherein m represents an integer between 0 and 1000, n represent an integer between 0 and 1000, G represents C 1-6 hydrocarbon group, optionally comprising one or two oxygen atoms and/or one or two nitrogen atoms, Z represents a nitrogen or a sulphur atom, R 1 and R 2 , are, independently from each other, a hydrogen atom or a C 1-3 alkyl group and o is 0 when Z is a sulphur atom or o is 1 when Z is a nitrogen atom.
16 . The process according to claim 3 , wherein X is an anion selected from the group consisting of carboxylate, β-diketonate, enolate, amide, silylamide, alkyl, cycloalkyl, alkoxy, aryl, aryloxy, alkoxyalkyl, alkoxyaryl, aralkoxy, aralcoyl and alkylaryl groups having from 1 to 20 carbon atoms, halide, carbonate and cyanide.
17 . The process according to claim 3 , wherein said ligand L is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, diethylaminoethanol, dimethylaminomethanol, diethylaminomethanol, 2-aminobutanol, ephedrine, valinol, prolinol, 2-(Diisopropylamino) ethanol, 2-{[2-(Dimethylamino)ethyl] methylamino} ethanol, 1,3-Bis(dimethylamino)-2-propanol, 2-[2-(Dimethylamino) ethoxy] ethanol, 1-Dimethylamino-2-propanol, cinchonidine, quinine and quinidine.
18 . The process according to claim 3 , wherein the substrate is a linear or branched, aliphatic or cyclic, saturated or unsaturated ketone or aldehyde selected from the group consisting of butanal, pentanal, hexanal, trans-hex-2-en-1-al, heptanal, octanal, decanal, dodecanal, acroleine, methacroleine, crotonaldehyde, prenal, citral, retinal, campholenic aldehyde, cinnamic aldehyde, hexylcinnamic aldehyde, formylpinane, nopal, benzaldehyde, cuminic aldehyde, vanillin, salicylic aldehyde, hexan-2-one, octan-2-one, nonan-4-one, dodecan-2-one, methyl vinyl ketone, mesityl oxide, acetophenone, cyclopentanone, cyclohexanone, cyclododecanone, cyclohex-1-en-3-one, isophorone, oxophorone, carvone, camphor, beta-ionone, geranylacetone, 3-methyl-cyclopenta-1,5-dione, 3,3-dimethyl-5-(2,2,3-trimethyl-cyclopent-3-en-1-yl)-pent-4-en-2-one and 2-pentylcyclopenten-2-one.
19 . The process according to claim 3 , wherein the substrate is an ester or lactone selected from the group consisting of alkyl and aryl acetates, propionates, butyrates, isobutyrates, benzoates, acrylates, crotonates, cinnamates, cis-3-hexenoates, sorbates, salicylates, 10-undecylenates, oleates and linoleates, fatty esters of natural or synthetic origin, caprolactone, butyrolactone, dodecalactone, diketene and sclareolide.
20 . The process according to claim 3 , wherein the substrate is an animal or vegetable fat, which is at least one oil selected from the group consisting of trioleine, peanut oil, sunflower oil, soya oil, olive oil, colza oil, sesame oil, grapeseed oil, linseed oil, cacao butter, cotton oil, copra oil, coconut oil, palm oil, jojoba oil, palm kernel oil, whale sperm oil, and pork, beef, mutton, or chicken fat.