The synthesis of 2-(5-Phenylthiazol-4-y1)benzoic acids

Abstract

The four-step synthesis of 2-(5-phenylthiazol-4-yl)benzoic acid (2a), and its 2-amino derivatives (2b), required for testing as potential plant growth regulators, is described. The α-bromo ketone (9b) was conveniently prepared from commercially available 3- benzylidenephthalide (8) in two steps, and in turn formed the thiazole esters (12) on treatment with either a mixture of formamide and phosphorus pentasulfide or thiourea. Hydrolysis of the esters (12) furnished the above benzoic acids.