Iodine(III)-Mediated Trifluoroacetylation of a C(sp²)–H or C(sp)–H Bond with Masked Trifluoroacyl Reagents

A novel strategy for incorporating a trifluoroacetyl functionality into a range of structurally varied unsaturated bonds was developed by using PhI(OCOMe)2 as an oxidant with a masked trifluoroacyl reagent as a trifluoroacetyl radical precursor. The oxidative decarboxylation of the masked trifluoroacyl precursor followed by a tandem radical process provides versatile access to 5-exo-trig cyclization of N-arylacrylamides, direct C(sp2)–H trifluoroacetylation of quinolines, isoquinoline, 2H-indazole, and quinoxalin-2(1H)-ones, and C(sp)–H trifluoroacetylation of alkynes. This protocol is characterized by mild reaction conditions, operational simplicity, and broad functional group compatibility.