Hydrogen bonds promote site-selective phenol functionalization enabled by Cl- anion


Most of studies for hydrogen bonds focus on the static model especially between two polar atoms. In contrast, introducing the third polar atom may emerge the competitive hydrogen bonds, which would represent a distinct perspective to perturb the catalytic chemical transformation. Herein, we report quantum mechanics calculations and quasi-classical direct dynamics simulations that demonstrate a triangle form of proton accepters enabled by Cl- anion can afford diverse hydrogen bonds, which control the reactivity and selectivity of Rh catalyzed phenol functionalization. A redox mechanism for carbene insertions with notable ligand effect was discovered and supported by both calculations and the experimental kinetic isotopic effect. The quaternary ammonium additive can stabilize key oxonium ylide intermediates with O-H…Cl hydrogen bonds that inhibit the common O-H insertion and promote the carbene C-H insertion product. The dynamic hydrogen bonds coupling with Rh complex dissociation may result in an intermediate shuttle of oxonium ylides, which unify the site-selective of the direct phenol functionalization.


Supplementary material

Electronic supplementary information
Mechanisms of Friedel-Crafts-type electrophilic aromatic substitution (SEAr); isotopic experiment; original data of figures in main text; comparison results for ωB97X-D, B3LYP-D3 and M11 in reaction mechanism; detailed dynamic simulations and cartoons for trajectories; the total energies and Cartesian coordinates of calculated structures.
Supporting Information for trajectory videos
quasi-classical direct dynamics trajectories