Heterocyclic syntheses with malonyl dichloride. Part 13. 6-Chloro-4-hydroxy-2-oxopyran-3-carboxanilides from N-sulphinylanilines and further reactions of malonyl dichloride with thiocyanates

Abstract

N-Sulphinylanilines react with malonyl dichloride to give 6-chloro-4-hydroxy-2-oxopyran-3-carboxanilides with loss of the sulphoxide moiety as thionyl chloride. Milder conditions and electron-withdrawing substituents do not alter the course of the reaction of thiocyanates with malonyl dichloride to give 2-substituted-thio-7-chloro-4H,5H-pyrano[3,4-e][1,3]oxazine-4,5-diones.