Sequential Protocol for C(sp3)–H Carboxylation with CO2: Transition-Metal-Catalyzed Benzylic C–H Silylation and Fluoride-Mediated Carboxylation

One of the most challenging transformations in current organic chemistry is the catalytic carboxylation of a C(sp3)–H bond using CO2 gas, an inexpensive and ubiquitous C1 source. A sequential protocol for C(sp3)–H carboxylation by employing a nitrogen-directed, metal-assisted, C–H activation/catalytic silylation reaction in conjunction with fluoride-mediated carboxylation with CO2 was established. The carboxylation proceeded only at the benzylic C(sp3)–Si bond, not at the aromatic C(sp2)–Si, which is advantageous for further manipulations of the products.