A facile synthesis of 2,4-diaza-1-borines from anilines

A general synthesis of diazaborines is described with the in situ preparation of amidines from anilines using a nitrile and AlCl3, followed by the addition of BCl3 and heating. The diazaborines were isolated as hydrochlorides in pure form and, in the case of 5, the structure was confirmed by an X-ray analysis.