Tetrabutylammonium iodide-catalyzed oxidative coupling of enamides with sulfonylhydrazides: synthesis of β-keto-sulfones.

A facile synthetic route towards pharmaceutically interesting β-keto-sulfone derivatives by tetrabutylammonium iodide (TBAI)/tert-butyl hydroperoxide (TBHP) mediated oxidative coupling of readily prepared enamides with economical sulfonylhydrazides is described. The corresponding β-keto-sulfone compounds were obtained in moderate to good yields. The present method is metal-free and base-free and shows tolerance to a variety of functional groups.