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(sp(3))-H bond using CO2 gas, an inexpensive and ubiquitous Cl source. A sequential protocol for C(sp(3))-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(sp(3))-Si bond, not at the aromatic C(sp(2))-Si, which is advantageous for further manipulations of the products.