Synthesis of 2,3-Disubstituted Pyrroles by Lewis Acid Promoted Cyclization of N -Sulfonyl Vinylogous Carbamates and Amides.

A three-step sequence to construct pyrroles from three components including 2,2-dimethoxyethylamine, aryl/alkyl sulfonyl chlorides and alkynes bearing electron-withdrawing groups is presented. The pyrroles are proposed to arise via a 5- exo -trig cyclization proceeding through both oxocarbenium and N -sulfonyliminium ions. This modular route allows for the variability at the N -sulfonyl group, the C2 and C3 substituents for rational vectoring of the pyrrole nucleus for downstream processes.