Patent ID: 7638542
Filing Date: 2009-12-29
Classification: A61P,C07C,C07D

Abstract:
1. A process for preparing 2-amino-6-alkyl-amino-4,5,6,7-tetrahydrobenzothiazoles of formula (I) wherein the asterisk (*) indicates the presence of an asymmetric carbon and R 1 is a linear or branched C 1 -C 6 alkyl group; their enantiomers or mixtures thereof, hydrates of pramipexole or pharmaceutically acceptable salts, comprising the following steps: (a) reacting a compound of formula (II)  wherein the asterisk (*) and R  wherein R  optionally in the presence of an acid and a solvent 1, to form an enamine of formula (III)  wherein the asterisk (*), R (b) optionally removing said acid and said solvent 1, and then reacting the compound of formula (III) with sulfur in the presence of a solvent 2 to obtain the compound of formula (IV)  wherein the asterisk (*) and R (c) reacting the compound of formula (IV) with cyanamide to obtain the compound of formula (I).