Kinetically Stable Boron-Heteroatom Bonds

Achieving kinetic stability of hydrolytically labile bonds remains a persistent goal of chemistry. The present study investigates the kinetic stability of boron-heteroatom bonds in N-methyliminodiacetic acid (MIDA) boronates. The hemilabile nature of the ligand has enabled the synthesis of molecules that would otherwise be considered too hydrolytically labile. Depending on the structure, acid-promoted migration of the boryl substituent was found to produce molecules with boron bound to nitrogen in different oxidation states. The formation of azidoboronate over aminoboronate is a particularly interesting consequence of kinetic stabilization and is at odds with the expectedly low-energy path to nitrogen gas elimination. By focusing on the unusual stability of boron-heteroatom bonds in different settings, this study contributes to the development of fundamental aspects of organoboron chemistry and offers a path to versatile building blocks that should find widespread utility in chemistry.