Intermolecular cascade annulations of N-(arylsulfonyl)acrylamides with dual C(sp3)–H bonds: divergent access to indanes and pyrrolidin-2-ones

A new divergent intermolecular cascade annulation reaction of N-(arylsulfonyl)acrylamides with dual alkyl C(sp3)–H bonds for producing two types of five-membered rings, indanes and pyrrolidin-2-ones, is described. By using cycloalkanes and common alkanes as a one-carbon unit, an intermolecular [4+1] cascade carboannulation of N-(arylsulfonyl)acrylamides was achieved via a sequence of three C–H bond functionalization/aryl migration/desulfonylation that enables the formation of three C–C bonds and one N–H bond. When the one-carbon unit was changed to cycloalkyl ethers, the alternative intermolecular [4+1] cascade heteroannulation reaction occurred and allowed the construction of two C–C bonds and one C–N bond through dual C–H bond functionalization, aryl migration and desulfonylation cascades.