Metal-free regioselective cascade sulfonylation–cyclization of 3-aza-1,5-enynes with sulfur dioxide and aryldiazonium tetrafluoroborates to construct 1,2-dihydropyridines

Abstract

Radical cascade cyclization of tethered alkynes has emerged as an efficient tool to construct small but complex cyclic compounds. However, it currently relies on aryl or heteroaryl-tethered alkynes to give benzene-fused molecules. Herein, we describe a regioselective cascade cyclization of vinyl-tethered alkynes, 3-aza-1,5-enynes. This method features good functional group compatibility and mild conditions and provides an environmentally friendly way to construct 1,2-dihydropyridines.