Ortho-2,6-di:chloro-anilino phenylacetic acid prepn. - by reaction of isatin and 2,6-di:chloro-iodo-benzene to 2,6-di:chloro-indole-2,3-di:one converted to tosyl hydrazone and reduced

摘要

Process for the prepn. of ortho-2,6-dichloroanilino)-phenylacetic acid (I) comprises a) reaction of isatin (II) with 2,6-dichloro-iodo-benzene (III) to give 1-(2,6-dichlorophenyl)-indole-2,3-dione (Iv), b) (IV) is converted to the tosyl hydrazone (V) which is reduced with sodium borohydride (NaBH4) in acid soln. at 60-70 degrees C. (I) is a known antiinflammatory, analgesic and antipyretic used in the form of the sodium salt, known as Dichlophenac. Known process (GB 1257190) used as difficult five stage process to produce (IV) which is reduced by a Wolff-Kishner reaction. These reactions produce many be prods. which are difficult to remove and lead to 50% yields of (I). The present process gives an easy route to (IV); produces high yields of (I) and is convenient for industrial scale prodn.