Integration of oxidative arylation with sulfonyl migration: one-pot tandem synthesis of densely functionalized (NH)-pyrroles
A one-pot synthesis of 2-aryl-3-alkyl/aryl-sulfonyl-(NH)-pyrroles from N-sulfonylpyrroles, developed for the first time, via palladium-catalyzed oxidative C-2 arylation followed by sulfonyl migration is described. The simple, easy access to the highly functionalized free-NH pyrroles secures opportunities for the preparation of compounds with promising biological activities in contemporary organic synthesis. The event of sulfonyl migration from pyrrole-N to C-3 is thermodynamically favored as revealed by density functional methods. The different plausible mechanisms for the migration of the sulfonyl group are also discussed.