Patent ID: 8203002

Claim:
Process for the preparation of pramipexole, or a pharmaceutically acceptable salt thereof, comprising the alkylation of a compound of formula (VII) as the single (S) enantiomer wherein Ra is a free or protected amino group, R 3 is hydrogen or a R 4 —O—CO—group, wherein R 4 is straight or branched C 1 -C 4 alkyl and the asterisk * indicates the stereogenic carbon atom, to obtain a compound of formula (VIII) wherein Ra, R 3 and the asterisk * are as defined above, and, if necessary, the removal of the primary amino-protecting group and/or of the R 4 —OR—CO— group from the secondary amino group and, if desired, its conversion to a pharmaceutically acceptable salt thereof, characterized in that: a) a compound of formula (VII), wherein Ra is a protected amino group and R 3 is as defined above, as the single (S) enantiomer, is prepared by rearrangement of a compound of formula (I), as the single (S) enantiomer, wherein R is a protected amino group; and the asterisk * indicates the stereogenic carbon atom, via formation of isocyanate, and subsequent addition of a nucleophilic solvent or subsequent quenching in water in the presence of an acidic agent; or b) a compound or formula (VII), wherein Ra is a free amino group and R 3 is hydrogen, as the single (S) enantiomer, is prepared by rearrangement of a compound of formula (I), as the single (S) enantiomer, via formation of isocyanate, and subsequent addition of water, to obtain a compound of formula (Ie) wherein R′ has the same meaning as R defined above, and subsequent hydrolysis.