Protection of Boronic Acids Using a Tridentate Aminophenol ONO Ligand for Selective Suzuki–Miyaura Coupling

Boronic
acid protecting group chemistry powerfully enhances the
versatility of Suzuki–Miyaura cross-coupling. Prominent examples
include trifluoroborate salts, N-methyliminodiacetic
acid (MIDA) boronates, and 1,8-diaminonaphthalene boronamides. In
this work, we present a bis(2-hydroxybenzyl)methylamine (BOMA) ligand
that forms tridentate complexes with boronic acids much like the MIDA
ligand but the deprotection is facilitated by organic acids. The BOMA
boronates showed considerable stability in both aqueous base and acid,
and a variety of chemoselective reactions were performed on these
boronates, including selective Suzuki–Miyaura coupling, palladium-catalyzed
borylation, ester hydrolysis, alkylation, lithiation–borylation,
and oxidative hydroxydeboronation.