Sterically demanding Csp2(ortho-substitution)-Csp3(tertiary) bond formation via carboxylate-directed Mizoroki-Heck reaction under extra-ligand-free conditions.

Construction of the sterically demanding Csp2(oS)-Csp3(T) bond was achieved by carrying out the Pd-catalyzed carboxylate-directed Mizoroki-Heck reaction under extra-ligand-free aqueous conditions. The cooperative role of the presence of water with the absence of phosphine ligand was proposed to accelerate the migratory insertion process considerably, delivering a broad substrate scope.