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

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 alpha-sulfonamidoethyl-alpha,beta-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.

Automated summary

By controlling the conditions, 3-acylpyrrolidines can be synthesized and further subjected to a domino reaction to afford the desired product 4-alkylidene-3,4-dihydro-2H-pyrroles.