Catalyst for asymmetric hydrogenation
This invention aims at providing a catalyst for producing an optically active aldehyde or an optically active ketone, which is an optically active carbonyl compound, by carrying out selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, particularly a catalyst which is insoluble in a reaction mixture for obtaining optically active citronellal which is useful as a flavor or fragrance, by carrying out selective asymmetric hydrogenation of citral, geranial or neral; and a method for producing a corresponding optically active carbonyl compound. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support, an optically active cyclic nitrogen-containing compound and an acid.
1. A catalyst for asymmetric hydrogenation of an α, β-unsaturated carbonyl compound, which comprises:
a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support;
an optically active cyclic nitrogen-containing compound; and
an acid,
wherein the optically active cyclic nitrogen-containing compound is a compound represented by the following general formula (1):
wherein ring A is a three- to seven-membered ring which may have a substituent, comprises at least one kind of atom selected from the group consisting of a carbon atom, a nitrogen atom, a sulfur atom, an oxygen atom and a phosphorous atom, and may be a fused ring structure; R 1 and R 2 each independently represent an hydrogen atom, an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an alkenyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, a carboxyl group which may have a substituent, alkoxycarbonyl group which may have a substituent, an amide group which may have a substituent, a siloxy group which may have a substituent, an aromatic heterocyclic ring which may have a substituent or an aliphatic heterocyclic ring which may have a substituent, wherein R 1 and R 2 do not represent a same substituent, and either R 1 or R 2 may be bonded to the ring A to further form a ring; and * represents an asymmetric carbon atom, and
the optically active cyclic nitrogen-containing compound does not include amino acids.
2. The catalyst for asymmetric hydrogenation according to claim 1 , wherein the metal is selected from the group consisting of nickel, ruthenium, rhodium, iridium, palladium and platinum.
3. A method for manufacturing an optically active carbonyl compound represented by the following general formula (3):
wherein R 3 , R 4 , R 5 and R 6 are the same as defined in the following formula (2), and two * mean that at least one * represents an asymmetric carbon atom,
wherein the method comprises conducting asymmetric hydrogenation of an α, β-unsaturated carbonyl compound represented by the following general formula (2) by using the catalyst for asymmetric hydrogenation according to claim 1 or 2 :
wherein R 3 , R 4 , R 5 and R 6 each independently represent an hydrogen atom, an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an alkenyl group which may have a substituent, an aryl group which may have a substituent, or an aralkyl group which may have a substituent, and a ring may be formed by R 3 and R 4 , R 3 and R 5 , R 3 and R 6 , R 4 and R 6 , or R 5 and R 6 ; and when a ring is not formed by R 3 and R 4 , or R 3 and R 5 , and R 4 does not represent a hydrogen atom, R 5 and R 6 may be the same or different from each other; and when a ring is not formed by R 3 and R 4 , or R 3 and R 5 , and R 4 represents a hydrogen atom, R 5 and R 6 do not represent a hydrogen atom and are different from each other.
4. The method according to claim 3 , wherein the α, β-unsaturated carbonyl compound is geranial, neral or citral.
5. The method according to claim 3 , wherein the α, β-unsaturated carbonyl compound is ketones having a five- to sixteen-membered ring.
6. The catalyst for asymmetric hydrogenation according to claim 1 , wherein the carboxyl group in R 1 and R 2 is selected from the group consisting of an acetoxy group, a n-propanoyloxy group, an isopropanoyloxy group, a n-butanoyloxy group, a 2-butanoyloxy group, an isobutanoyloxy group, a tert-butanoyloxy group, a n-pentanoyloxy group, a 2-methylbutanoyloxy group, a 3-methylbutanoyloxy group, a 2,2-dimethylpropanoyloxy group, a n-hexanoyloxy group, a 2-methylpentanoyloxy group, a 3-methylpentanoyloxy group, a 4-methylpentanoyloxy group, a 5-methylpentanoyloxy group, a cyclopentanoyloxy group, a cyclohexanoyloxy group, a dicyclopentylacetoxy group, a dicyclohexylacetoxy group, a tricyclopentylacetoxy group, a tricyclohexylacetoxy group, a phenylacetoxy group, a diphenylacetoxy group, a triphenylacetoxy group, a benzoyloxy group, and a naphthoyloxy group.