Process for manufacturing 1,6-dihydro-6-oxo-4-pyridazine carboxylic acid
申请人:BOEHRINGER INGELHEIM INTERNATIONAL GMBH
公开号:EP2857387A1
公开(公告)日:2015-04-08
The present invention provides a process for manufacturing 6-oxo-1 H-pyridazine-4-carboxylic acid 5 comprising - (a) reacting dimethyl 2-methylenebutanedioate with hydrazine to obtain methyl 6- oxohexahydropyridazine-4-carboxylate 11; - (b) oxidizing methyl 6-oxohexahydropyridazine-4-carboxylate 11 with a suitable oxidizing agent to methyl 6-oxo-1 H-pyridazine-4-carboxylate 4a; - (c) isolating methyl 6-oxo-1 H-pyridazine-4-carboxylate 4a; - (d) hydrolyzing methyl 6-oxo-1 H-pyridazine-4-carboxylate 4a in the presence of an aqueous base or acid to the 6-oxo-1 H-pyridazine-4-carboxylic acid 5.