Process for the preparation of a novel 1-phthalazone

摘要

Preparation of a phthalazone of the formula I <IMAGE> by reaction of a compound of the formula II <IMAGE> in which R is an acyl group, with isobutylene in the presence of a catalyst and subsequently hydrolysing the product obtained. The said compound of the formula I is also alternatively prepared by reacting an acid halide of the compound of the formula II in the presence of a catalyst with tert.-butanol to give the compound of the formula III and then hydrolysing it. The compound obtained is a pharmaceutical active compound for the treatment of haemorrhage, thrombosis and atherosclerosis.