Resolution of 3-(methylamino)-1-(2-thienyl)propan-1-ol, a new key intermediate for duloxetine, with (S)-mandelic acid

摘要

The resolution of racemic 3-(methylamino)-1-(2-thienyl)propan-1-ol (3), a new key intermediate for duloxetine (1), was studied. The conditions were optimized for an industrial-scale resolution of 3 by using (S)-mandelic acid (4) as a resolving agent and 2-butanol containing two equimolar amounts of water as a solvent. The (S)-3･(S)-4･H2O diastereomeric salt was crystallized to give pure (S)-3 with >99.9% ee after liberation of the amine. Absolute configuration of liberated (-)-3 was determined as (S)-form by X-ray crystallography.