New studies of Rh-catalyzed addition of boronic acids under basic conditions in aqueous medium

Rh-catalyzed CC bond formation in neat water under basic conditions has been efficiently performed. The addition of various boronic acids to styrene, 2-vinylpyridine, and cyclic α,β-unsaturated ketones has been realized with high selectivity and yield. We have shown that m-TPPTC (tris(m-carboxyphenyl)phosphane trilithium salt) exhibited a higher reactivity compared to TPPTS. These couplings could also be conducted very efficiently under basic and phosphaneless conditions to give functionalized aryl derivatives. The benefits of the additional anionic ligand m-TPPTC lied in the successful recycling experiments of 1,4-addition of phenylboronic acid to cyclohexenone, with no loss of the water-soluble catalyst.