A process for the preparation of 1-phenyl-3-(4-chlorophenyl)-pyrazol-4-ylacetic acid and its calcium salt.

摘要

The invention relates to a process for preparing 1-phenyl-3-(4-chlorophenyl)-pyrazol-4-ylacetic acid, known under the generic name Lonazolac, and its calcium salt (Ca-Lonazolac). The process comprises the reductive hydrolysis of 1-phenyl-3-(4-chlorophenyl)-4-pyrazolecarboxaldehyde cyanohydrine using stannous chloride in a mixture of acetic acid, hydrochloric acid and preferably a catalytic amount of hydroiodic acid at elevated temperatures, and, if required, subsequent conversion of the acid into the calcium salt. The products are potent anti-inflammatory agents.