Patent ID: 6881868
Filing Date: 2005-04-19
Classification: C07C

Abstract:
1. A process for the preparation of compounds of formula I, wherein R 1 and R 2 are independently of one another H, C 1 -C 6 alkyl, C 1 -C 6 halogenalkyl, C 1 -C 6 alkoxy, C 1 -C 6 alkoxy-C 1 -C 6 alkyl, or C 1 -C 6 -alkoxy-C 1 -C 6 alkyloxy, and R 3 is C 1 -C 6 alkyl comprising a) reacting compound of formula II wherein R 1 and R 2 are as defined hereinbefore, with a compound formula III, wherein R 3 is as defined hereinbefore, to form a compound of formula IV, wherein R 7 is C 1 -C 12 alkyl, C 3 -C 8 cycloaxyl, phenyl or benzyl, b) isolating a cristalline compound IV, acylating the OH group of the compound of formula IV to a leaving group, and eliminating the living group at low temperatures in the presence of an alkali metal alcoholate or a secondary amide in the reaction mixture of the acylation process to form a compound of formula V, c) reducing the carbonic esters of formula V to form the alcohol of formula VI, d) hydrogenating the alcohol of formula VI in the presence of hydrogen and catalytic quantities of a metal complex as asymmetric hydrogenation catalyst, comprising metals from the group of ruthenium, rhodium and iridium, to which the chiral bidentate ligands are bonded, to form a compound of formula I.