Domino Synthesis of 4‐Alkylidene‐3,4‐dihydro‐2H‐pyrroles from Homopropargyl Sulfonamides and Aldehydes

Abstract

We describe a domino synthesis of 4‐alkylidene‐3,4‐dihydro‐2H‐pyrroles from aryl‐substituted homopropargyl sulfonamides and aldehydes promoted by cheap and easy‐to‐handle TsOH ⋅ H2O. The present reactions proceed through cyclocondensation of α‐sulfonamidoethyl‐α,β‐enone intermediates, which are formed by ring‐cleavage of 3‐acylpyrrolidines corresponding to aza‐Prins cyclized intermediates. By controlling the conditions, 3‐acylpyrrolidines can be obtained.