Rhodium(III)-Catalyzed Regioselective C-H Activation/Annulation for the Diverse Pyrazole-Core Substituted Furans

A novel and facile regioselective synthetic method for polyfunctionalized furans involving rhodium(III)-catalyzed pyrazole- or indazole-directed dual C-H functionalization with diazodicarbonyls has been developed. This strategy provides rapid access to diverse tetrasubstituted furans bearing various pyrazoles or indazoles. This unprecedented one-pot protocol proceeds via cascade C-H activation, metal-carbene formation, migratory insertion, intramolecular cyclization, and deprotonation.