BF3·Et2O promoted one-pot expeditious and convenient synthesis of 2-substituted benzimidazoles and 3,1,5-benzoxadiazepines

2-Substituted benzimidazoles and 3,1,5-benzoxadiazepines have been synthesized in excellent yields in a single pot by cyclodehydration of N-acyl-1,2-phenylenediamines and N,N′-diacyl-1,2-phenylenediamines prepared in situ from the corresponding 1,2-phenylenediamines and an acid chloride, respectively.