Salt Metathesis: Tetrafluoroborate Anion Rapidly Fluoridates Organoboronic Acids to give Organotrifluoroborates

Abstract

AbstractTetrafluoroborate (BF4−) has long been used as a spectator counter anion. Herein, we report an unprecedented salt metathesis between a variety of BF4− salts and a series of organoboronic acids yielding the corresponding organotrifluoroborates. We identified conditions for fast and efficient fluoridation (<1 h) with minimal workup. Fundamentally, this work discloses the proclivity of BF4− to exchange fluoride atoms with organoboronates, highlighting the lability of BF4−.