Patent ID: 6818423
Filing Date: 2004-11-16
Classification: C07B,C07C,C12P

Abstract:
A process for the preparation of chiral &agr;-hydroxycarboxylic acids of the formula (I) in which R1 is a C1-C2-alkyl radical optionally substituted by one or more halogen atoms and R2 is a C2-C3-alkyl radical optionally substituted by one or more halogen atoms, which comprises reacting a compound of the formula (II) in which R1 is as defined above, R2â€² is a C2-C3-alkylene radical optionally substituted by one or more halogen atoms, m can be equal to 0 or 1, R is a C1-C20-alkyl radical, a C5-C20-aryl radical, heteroaryl radical or a heterocyclyl radical, where the radicals can optionally be mono- or polysubstituted by substituents from the group consisting of C1-C4-alkyl, C1-C4-alkoxy, C1-C6-alkylthio, phenyl, benzyl, halogen, hydroxyl, nitro, carboxyl, esters, thioesters, carbonates, carbamates or urethanes, and X can be oxygen, sulfur, sulfinyl, sulfonyl, imino, C1-C6-alkylimino, xanthate, silyl, or, if m is equal to 0, halogen, in the presence of a cyanide group donor either enantioselectively with (R)- or (S)-hydroxynitrile lyase in an organic, aqueous or 2-phase system or in emulsion to give the corresponding (R)- or (S)-cyanohydrin of the formula (III) in which R1, R2â€², R, m and X are as defined above, or racemically to give the corresponding racemate of the cyanohydrin of the formula (III), then converting the compound of the formula (III) or its racemate by means of acidic hydrolysis into the corresponding acid of the formula (IV) in which R1, R2â€², R, m and X are as defined above, or its racemate, whereupon the cleavage of the group of the formula (V) (R)mâ€”Xâ€ƒâ€ƒ(V) is carried out, where in the case of the racemate a resolution is first carried out, and isolating the desired chiral &agr;-hydroxycarboxylic acid of the formula (I).