New, Scalable Process for the Preparation of 5-Acetyl-1 H -pyrazole-3-carboxylic Acid, a Key Intermediate of Darolutamide

A new, efficient process for the synthesis of 5-acetyl-1H- pyrazole-3-carboxylic acid, a versatile building block and the key inter-mediate of darolutamide, using diethyl pyrazole-3,5-dicarboxylate as the starting material is described. Contrary to the synthetic routes known from the literature, this procedure does not employ explosive di-azo reagents, moreover it is simple and safe, thereby suitable for scale-up.