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

Abstract

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.