Oxidative Trifluoroacetoxylation of 1°, 2°, and 3° Benzylic C(sp)-H Bond Donors Using -Trifluoroacetoxyquinuclidinium Salts under Photoredox Catalysis.

-Trifluoroacetoxyquinuclidinium trifluoroacetate was prepared from quinuclidine -oxide and (CFCO)O. Except for some electron-poor substrates, this reagent allows for the high-yielding oxidative trifluoroacetoxylation of 1°, 2°, and 3° benzylic C-H bonds under photocatalytic conditions. The trifluoroacetoxylation of an ibuprofen methyl ester allowed the selective functionalization of a 2° benzylic C-H bond. For alkylbenzenes, hydrogen-atom transfer from a benzylic C-H bond to a quinuclidine cation radical was proposed to be the reaction-product-determining step.