Cesium and Phenoxide Interaction Enabled by Rh Overrides the Innate Solvent-Mediated Chemoselectivity

DLPNO-CCSD(T) calculations are carried out to understand the distinctive chemoselectivity in a Rh(II)-catalyzed carbene insertion into a C(sp2)–H bond in unprotected phenols without preinstalled directing groups. As per the conventional rules of solvation and a separated ion pair in polar aprotic solvents like acetonitrile, the reaction should have resulted in an O–H insertion. However, our calculations reveal a transition state model that helps in overriding the innate chemoselectivity in acetonitrile. It involves an explicit participation of the added Cs2CO3 base, where the interaction between the phenoxide oxygen and Cs cation, but not as a metal-bound Cs phenoxide, is crucial for controlling the chemoselectivity. Our study will be helpful in developing further reactions with a broad catalyst, substrate, and solvent scope.