methodology for synthesizing 2,3-benzodiazepines and their analogues by means of phosphate-assisted acylation reaction of 1-arylpropan-2-ones with a carboxylic acid followed by hydrazine cyclization in a one-pot two-step manner. An unprotected amino group is tolerated in this reaction. This method provides a direct access to 2,3-benzodiazepines containing aromatic 7,8-dimethoxy and 1-p-aminophenyl groups,
New 5H-2,3-benzodiazepine derivatives of the formula ##STR1## wherein R is phenyl having a trifluoromethyl or halogen substituent, R.sup.1 is methyl, R.sup.2 is hydrogen, R.sup.3 is methoxy and R.sup.4 is methoxy, and the pharmaceutically acceptable acid addition salts thereof, are potent tranquilizers.