Cp*Ir(iii) and Cp*Rh(iii)-catalyzed annulation of salicylaldehydes with fluorinated vinyl tosylates

Abstract

A mild, selective and redox-neutral Cp*Ir(III)- and Cp*Rh(III)-catalyzed C–H activation/annulation of salicylaldehydes with fluorovinyl tosylates is reported. The use of monofluorovinyl tosylate favors the synthesis of C2- and C3-substitution-free chromones via C–H activation/β-F elimination/annulation, whereas difluorovinyl tosylate leads to the construction of C2-fluoroalkoxy chromones. Mild reaction conditions and good functional-group tolerance were observed. Further functionalization of the resulting chromones via halogenation, alkynylation, alkylation and hydrocyanation was successfully realized.