Silica supported fluoroboric acid as a novel, efficient and reusable catalyst for the synthesis of 1,5-benzodiazepines under solvent-free conditions

An efficient synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones under solvent-free conditions in the presence of a catalytic amount of HBF4–SiO2 is discussed. Cyclic and acyclic ketones reacted smoothly to furnish high yield of the products with selectivity in short reaction time.

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