合成路线1

Two different routes have been described for the preparation of title compound: 1) 3-Methyl-5-aminoisothiazole-4-carboxylic acid (I) is reacted with benzoyl chloride in acetone solution and in the presence of pyridine to yield the benzamide (II), which by reaction with SOCl2 is converted to the lactam (III). The reaction of lactam (III) with p-chloroaniline in anhydrous ethanol gives the p-chlorophenylamide (vratizolin). 2) The reaction of 3-methyl-5-benzoylamino-4-isothiazolecarboxylic acid (II) with chloroformic ethyl ester gives the mixed anhydride, which, when heated with p-chloroanitine in anhydrous ethanol forms title compound. Vratizolin is also a product of the reaction of the acid (II) with p-chloroaniline in the presence of dicyclohexylcarbodiimide.