Scandium triflate-catalyzed one-pot domino approach towards general and efficient syntheses of unsymmetrical 9-substituted xanthene derivatives

Abstract

A general and efficient one-pot cascade/tandem approach to synthesize unsymmetrical 9-aryl/heteroaryl xanthenes has been developed under extremely mild reaction conditions using 10 mol% Sc(OTf)₃ as a catalyst. This strategy has been further extended to synthesize 9-(thioaryl) xanthenes through tandem carbon–sulfur (C–S) and carbon–carbon (C–C) bond formation. Novel C–C and C–S bond cleavage promoted by Sc(OTf)₃ is also discussed during mechanistic investigation.