Synthesis of new dihydrooxathiino[2,3-b]quinoline

Abstract

A synthesis of new dihydrooxathiinoquinoline 4 is described. The key compound 6 was prepared by known methods from acetoacetanilide 1. A condensation of beta-chlorosulfide 6 in 75% aqueous sulfuric acid gave quinolone 5. Conversion of 5 to 4 was achieved by treatment with potassium hydroxide in ethanol solution.