A cascade indazolone-directed Ir(iii)- and Rh(iii)-catalyzed C(sp2)–H functionalization/[4 + 2] annulation of 1-arylindazolones with sulfoxonium ylides to access chemically divergent 8H-indazolo [1,2-a]cinnolines

Abstract

An indazolone-directed chemoselective synthesis of 8H-indazolo [1,2-a]cinnolines has been realized via a cascade Cp*Ir(III)- and Cp*Rh(III)-catalyzed C–H activation/cyclization reaction of 1-arylindazolones with sulfoxonium ylides. The strategy showcased broad substrate scope, high functional group compatibility, mild reaction conditions and was suitable for late-stage modification of drug molecules. Moreover, a preliminary mechanistic probe has been conducted and an exploratory reaction mechanism was proposed. This report represents the first example of an indazolone-directed Cp*Ir(III)-catalyzed C(sp²)–H activation reaction under solvent-free conditions, as well as the first protocol of a Cp*Rh(III)-catalyzed C(sp²)–H activation/oxidation/annulation reaction.