Reduction of C,N-chelated chloroborane: straightforward formation of the unprecedented 1H-2,1-benzazaborolyl potassium salt

Abstract

Reduction of C,N-chelated chloroborane [2-(CHNtBu)C₆H₄]BPhCl (1) with the potassium metal afforded (3,3′)-bis(1-Ph-2-tBu-1H-2,1-benzazaborole) (2). Compound 2 is formed via C–C reductive coupling reaction. Subsequent reduction of 2 with two equivalents of the potassium metal produced orange crystals of 1Ph-2tBu-1H-2,1-benzazaborolyl (Bab) potassium salt K(THF)(Bab) (3). Compound 3 is able to react with simple electrophiles (MeI or Me₃SiCl) resulting in the formation of substituted 1H-2,1-benzazaboroles.