Patent ID: 9000158
Filing Date: 2015-04-07
Classification: A61P,C07D

Abstract:
1. A process for preparing (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone, which process comprises: a) reacting racemic 6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone of formula II with a chiral tartaric acid derivative to form a first diastereomer salt and a second diastereomer salt, wherein the first diastereomer salt is a salt of (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative, and wherein the second diastereomer salt is a salt of (+)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative; and b) isolating (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone from the first diastereomer salt, wherein the chiral tartaric acid derivative is selected from the D- or L-isomer of di-p-anisoyl-tartaric acid, di-p-tolyl-tartaric acid or O,O′-dibenzoyl-tartaric acid.