PROCESS FOR PREPARING LEVOSIMENDAN AND INTERMEDIATES FOR USE IN THE PROCESS

摘要

In an embodiment, the present invention provides a process for preparing (−)-6-(4-aminophenyl)-5-methylpyridazin-3-(2H)-one, 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 obtain a diastereomeric salt of (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative; and b) reacting the diastereomeric salt with a base to obtain (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone. The (−)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone may be used to prepare levosimendan.