Attempted halogenation of ambiphilic 1,2,3-benzodiazaborines: Balancing Lewis acidity and Lewis basicity

Abstract

The inherent Lewis basic character of 1,2,3-diazaborines (DAB) prevents straightforward conversion of their prevalent B–OH motif into a B–Hal group with BX3 due to competitive ortho-directed C−H borylation. A synthetic strategy to intermittently mask the Lewis basicity was developed, permitting formation of an unprecedentedly Lewis acidic ClDAB, as well as isolation of the first intermolecular adducts and a boronium ion congener of benzodiazaborines.