Patent ID: 8703955

Claim:
A process for the resolution of (R,S)-tetrahydropapaverine (THP) (I) with an optically active arylpropionic acid, in admixture with an optically active acid or with an inorganic acid, in a suitable solvent system comprising: a) contacting (R,S)-THP (I) with an optically active arylpropionic acid, in admixture with an optically active acid or with said inorganic acid, in a suitable solvent system, b) separating the diastereoisomeric compound of (R)-THP precipitated from the mixture, c) recovering (R)-THP (Ia) from the separated diastereoisomer; and/or optionally d) recovering (S)-THP (Ib) from the mother liquor wherein the ratio of equivalents of optically active arylpropionic acid to (R,S)-THP is in the range of 0.3:1-1:1 with respect to (R,S)-THP.