Patent ID: 7041845

Claim:
A process for preparing an optically active 5-hydroxy-3-ketoester of the formula A1 or A2 or one of the tautomers thereof, wherein R 1 and R 2 independently of each other represent hydrogen or a group which is selected from among C 1 –C 8 -alkyl, C 3 –C 8 -cycloalkyl, C 6 –C 10 -aryl and C 1 –C 8 -alkylene-C 6 –C 10 -aryl, optionally with one, two or three substituents, selected from among hydroxy, halogen, C 1 –C 4 -alkoxy and CF 3 , where R 1 and R 2 do not simultaneously have the same meaning, and R 3 denotes a group selected from among C 1 –C 8 -alkyl, C 1 –C 4 -Haloalkyl, C 6 –C 10 -aryl-C 1 –C 8 -alkylene and trihydrocarbylsilyl, characterised in that a racemic mixture of a 5-hydroxy-3-ketoester of formula A wherein R 1 , R 2 and R 3 are as hereinbefore defined, is resolved into the two enantiomeric 5-hydroxy-3-ketoester A1 and A2 by preparative high performance liquid chromatography (HPLC) over a chiral carrier material, wherein the chiral carrier material is selected from the group consisting of tris(3,5-dimethylphenylcarbamate) -amylose, tris[(S)-α-methylbenzvlcarbamate]-amylose, tris(3,5-dimethyphenylcarbamate) -cellulose, tris(4-methylbenzoate)-cellulose, cellulose triacetate, cellulosetribenzoate, tris(phenylcarbamate)-cellulose, tris(4-chlorophenylcarbamate)-cellulose, cellulosetricinnamate and cellulosetribenzoate.