Method for producing chiral α,β-epoxy ketones
A process is claimed for the enantioselective epoxidation of α,β-unsaturated ketones, in which a compound of the general formula I, is reacted with an oxidizing agent to form α,β-epoxy ketones of the general formula II, in which R 1 , R 2 , R 3 are as defined above. The α,β-epoxy ketones of the general formula II can be obtained in good yields and outstanding enantioselectivities from α,β-unsaturated ketones of the general formula I by epoxidation with hydrogen peroxide in the presence of a chiral catalyst, such as amino compounds and their acid addition salts.
1. A process for the enantioselective epoxidation of α,β-unsaturated ketones, said process comprising reacting a compound of the formula I,
in which
R 1 is a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 30 carbon atoms, which is substituted or unsubstituted and may have one or more heteroatoms in the chain,
R 2 is hydrogen, a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 30 carbon atoms, which is substituted or unsubstituted and may have one or more heteroatoms in the chain, or an aryl group or heteroaryl group, which is substituted or unsubstituted,
R 3 is hydrogen, a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 30 carbon atoms, which is substituted or unsubstituted and may have one or more heteroatoms in the chain, or an aryl group or heteroaryl group, which is substituted or unsubstituted,
R 1 , R 2 , and R 3 may be identical or different,
and the radical R 1 may, with the radicals R 2 and R 3 , form a ring, which may have 5 to 20 members, be saturated or unsaturated, alicyclic or heteroalicyclic, and is substituted or unsubstituted,
with an oxidizing agent to form a 3-epoxy ketone of the formula II,
in which R 1 , R 2 , R 3 are as defined above,
wherein said reacting is carried out in the presence of a chiral catalyst, said chiral catalyst is selected from the group consisting of amines and their acid addition salts, and said amines have the formula III:
NH 2 R 4
in which
R 4 is an optionally substituted hydrocarbon group having 1 to 30 carbon atoms, or an optionally substituted, heteroatom-containing hydrocarbon group, and their acid addition salts.
2. The process as claimed in claim 1 , wherein the oxidizing agent is selected from hydrogen peroxide, alkyl peroxides, sodium hypochlorite, peracids, iodoso compounds and borates.
3. The process as claimed in claim 2 , wherein an aqueous hydrogen peroxide solution is used as oxidizing agent.
4. The process as claimed in claim 1 , wherein the chiral catalyst is selected from chiral amines of the formula III, from addition salts of achiral amines of the formula III with chiral acids, and from addition salts of chiral amines of the formula III with achiral or chiral acids.
5. The process as claimed in claim 4 , wherein the chiral acids are selected from chiral organic phosphoric acids, phosphorimides, sulfuric acids, sulfonic acids, sulfonylimides, carboxylic acids, and imides.
6. The process as claimed in claim 5 , wherein the chiral acid is derived from binaphthol.
7. The process as claimed in claim 6 , wherein the chiral acid is selected from organic chiral phosphoric acids having the formula IV,
in which
R 6 is H, an optionally substituted hydrocarbon group, or an optionally substituted, heteroatom-containing hydrocarbon group.
8. The process as claimed in claim 1 , wherein the amine having the formula III is a primary amine.
9. The process as claimed in claim 8 , wherein the primary amine is selected from compounds having the formulae V, VI and/or VII
in which
R 7 is an optionally substituted hydrocarbon group, or an optionally substituted, heteroatom-containing hydrocarbon group, and
R 8 is an optionally substituted hydrocarbon group, or an optionally substituted, heteroatom-containing hydrocarbon group,
R 7 and R 8 may be identical or different,
and the radicals R 7 and R 8 may form a ring, which may have 4 to 20 members, be saturated or unsaturated, alicyclic or heteroalicyclic, and is substituted or unsubstituted, and
R 9 is H, or a group —OR 10
in which
R 10 is hydrogen, an optionally substituted hydrocarbon group having 1 to 30 carbon atoms, or an optionally substituted, heteroatom-containing hydrocarbon group.
10. The process as claimed in claim 1 , wherein “substituted” means substitution by one or more substituents selected from the group consisting of C 1 -C 4 -alkyl, C 1 -C 4 -alkenyl, aryl, heteroaryl, halogen, NO 2 and amino.
11. The process as claimed in claim 7 , wherein R 6 is an unsubstituted or substituted, saturated or unsaturated, branched or linear C 1 -C 20 -alkyl group, C 2 -C 20 -alkenyl group, C 2 -C 20 -alkynyl group or aryl group.