Microwave assisted metal-/oxidant-free cascade electrophilic sulfenylation/5-endo-dig cyclization of 2-alkynylanilines to generate diversified 3-sulfenylindoles

Abstract

A metal-/oxidant-free sustainable protocol for the synthesis of 3-sulfenylindoles based on electrophilic cyclization of 2-alkynylanilines has been developed under microwave irradiation. Herein, catalytic amount of iodine and stoichiometric amount of sulfonyl hydrazides were employed as catalyst and electrophiles respectively to induce the 5-endo-dig cyclization of 2-alkynylanilines. This strategy allows a wide substrate scope, demonstrates good functional group tolerance, utilizes easily available reagents and overcome multistep synthesis.