Patent ID: 8193391

Claim:
A process for preparing an acid addition salt of an optically active organic acid and a compound of formula III′ where R 1 is selected from the group consisting of: H, and C 1 -C 3 alkyl; and R 2 is selected from the group consisting of C 1 -C 3 alkyl; or a salt thereof, comprising the steps of: a) providing a compound of formula II where R 1 and R 2 are defined as above; b) reacting compound of formula II with compound of formula I wherein R 3 is selected from the group consisting of CH 3 , Cl, Br, I, CHO, and CN, in the presence of an acid; and c) optically resolving the crude product obtained in step b) by adding an optically active organic acid to the non-purified reaction product obtained in step b) in order to obtain the acid addition salt of an optically active organic acid and compound of formula III′ wherein the overall yield of the optically active organic acid salt of compound of formula III′ is at least 65% and the optical purity of the compound is at least 97% ee.