A mild and efficient synthesis of benzodiazepines using La(NO3)3 · 6H2O as a catalyst under solvent-free conditions

An efficient and clean synthesis of benzodiazepines is described by the reaction of o-phenylenediamine with different types of methyl/methylene ketones in the presence of catalytic amounts of La(NO3)3 · 6H2O under solvent-free conditions at room temperature in excellent yields.