Deprotonation of a Hydridoborate Anion

摘要

The first deprotonation of a borohydride anion was achieved by treatment of BH(CN)(3)(-) with strong nonnucleophilic bases, which resulted in the formation of alkalimetal salts of the tricyanoborate dianion B(CN)(3)(2-) in up to 97 yield and 99.5 purity. BH(CN)(3)(-) is less acidic than (Me3Si)(2)NH but a stronger acid than iPr(2)NH. Less sterically hindered, more nucleophilic bases such as PhLi and MeLi mostly attack a CN group under formation of imine dianions RC(N) B(CN)(3)(2-), which can be hydrolyzed to ketones of the RC(O) B(CN)(3)(-) type. The boron-centered nucleophile B(CN)(3)(2-) reacts with CO2 and CN+ reagents to give salts of the B(CN)(3)CO2(2-) dianion and the tetracyanoborate anion B(CN)(4)(-), respectively, in excellent yields.