Patent ID: 7019161

Claim:
A process for the preparation of optically active compounds of the formula IA or IB as free bases or as acid addition salts thereof, in which R 2 is hydrogen, R 3 is—in each case unsubstituted or substituted—phenyl or C 1 –C 4 alkyl, R 4 is hydrogen or C 1 –C 10 alkyl, and R 5 is hydrogen or C 1 –C 4 alkyl, which process comprises (a) hydrogenating a compound of the formula II in which R 1 is hydrogen or C 1 –C 4 alkyl, and R 6 is unsubstituted or substituted phenyl, and R 2 , R 3 , R 4 and R 5 are as defined for compounds of the formula IA or IB, in the presence of a catalytically active amount of a heterogeneous platinum on alumina hydrogenation catalyst with saturation of the double bond to give compounds of the formulae IIA and/or IIB, in which the radicals R 1 and R 6 are as defined for compounds of the formula II and the radicals R 2 , R 3 , R 4 and R 5 are as defined for compounds of the formulae IA and IB; (b) then converting the product obtained with an acid of the formula [H + ] n X n− , in which n is 1 and X is an acid radical, into a corresponding acid addition salt of the formula(e) IIIA and/or IIIB, in which n is 1, X n− is an acid anion, R 1 and R 6 are as defined for compounds of the formula II, and R 2 , R 3 , R 4 and R 5 are as defined for compounds of the formulae IA and IB; which is (c) converted by removal of the chiral auxiliary group R 1 R 6 CH— into a corresponding salt of the formula(e) IVA and/or IVB in which n and the radicals R 2 to R 5 and X n− are as defined above, and, optionally, (d) the acid addition salt of the formula IVA or IVB obtained is converted in the presence of a base into the free compounds of the formula IA or IB; and/or, optionally, the group R 5 is removed from an ester of the formula IVA or IVB, if R 5 is not hydrogen.