| abstract |
The invention relates to a process for the preparation of 6,7-methylenedioxy-4 (1H) -oxo-cinnoline-3-carboxylic acid. The process can be used in the pharmaceutical industry to make this compound as a valuable intermediate for chemotherapeutic agents. The aim of the invention was to develop a simplified compared to the prior art method for producing this interconnect. The goal was achieved by a novel cyclization of Mesoxalsaeure-3,4-methylenedioxy-phenylhydrazone with Friedel-Crafts catalysts, in particular derivatives of phosphoric acid, in the presence of carboxylic anhydrides. The resulting 6,7-methylenedioxy-4 (1H) -oxo-cinnoline-3-carboxylic acid can be purified by treatment with an alkaline solution with acid or recrystallization. |