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

Abstract

DLPNO-CCSD(T) calculations are carried out to understand the distinctive chemoselectivity in a Rh(II)-catalyzed carbene insertion into a C(sp 2 )−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 Cs 2 CO 3 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.