Patent ID: 8669399

Claim:
A process for preparing a compound according to formula (I) wherein R 1 , R 2 and R 3 are each independently selected from the group consisting of H and C 1-4 -aliphatic residues, or a physiologically acceptable acid addition salt thereof, according to alternative A said process comprising the steps of: (a-I) hydrogenating a compound according to formula (A-I-a): wherein R 1 , R 2 and R 3 in each case have the above defined meanings, to a compound according to formula (A-II): wherein R 1 , R 2 and R 3 have the above defined meanings, (a-II) reducing the compound according to formula (A-II) to a compound according to formula (I), and (a-III) optionally converting the compound according to formula (I) into a physiologically acceptable acid addition salt thereof.