Abstract: 1,4-Benzodiazepine derivatives of the formula, ##STR1## wherein R.sub.1 is hydrogen, a lower alkyl, a haloalkyl, a cycloalkylalkyl, an alkoxyalkyl, an acyloxyalkyl, an alkylthioalkyl, an alkylaminoalkyl, a dialkylaminoalkyl, a hydroxyalkyl, carbamoyl, or an N-alkylcarbamoyl; R.sub.2 is hydrogen or a lower alkyl; X is hydrogen, a halogen, nitro, or trifluoromethyl; A is a group of the formula, ##STR2## (wherein Y and Z each represent hydrogen, a halogen, a lower alkyl, or nitro) and a salt thereof, are prepared by reacting a 1,4-benzodiazepin-2-one compound of the formula, ##STR3## wherein R.sub.1, R.sub.2, X, Y and Z are the same as defined above, with diborane in an inert solvent.