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