TBPB-initiated cascade cyclization of 3-arylethynyl-[1,1′-biphenyl]-2-carbonitriles with sulfinic acids: access to sulfone-containing cyclopenta[gh]phenanthridines

Abstract

A novel TBPB-initiated cascade cyclization of 3-arylethynyl-[1,1′-biphenyl]-2-carbonitriles with sulfinic acids via C–S, C–C and C–N bond formation for the synthesis of 3-sulfonated cyclopenta[gh]phenanthridines under metal-free conditions has been developed. This protocol features mild conditions, good functional group tolerance and a broad substrate scope. By using this protocol, a variety of potentially bioactive 3-sulfonated cyclopenta[gh]phenanthridines were facilely synthesized via direct annulation.