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

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.