Iodine(III)-Mediated Trifluoroacetylation of a C(sp 2 )-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(sp 2 )-H trifluoroacetylation of quinolines, isoquinoline, 2 H -indazole, and quinoxalin-2(1 H )-ones, and C(sp)-H trifluoroacetylation of alkynes. This protocol is characterized by mild reaction conditions, operational simplicity, and broad functional group compatibility.