Intramolecular borylation reaction catalyzed by Lewis acid: preparation of 1H-2,1-benzazaborole derivatives

It has been found that 1H-2,1-benzazaboroles can be prepared by the interaction of substituted benzylaminochloroboranes with Al2Cl6 in CH2Cl2 at 0 degrees C, the C-13 NMR spectroscopy data obtained being in favour of an electrophilic substitution mechanism involving formation of cationic complexes as reactive intermediates.