Simultaneous reduction of the nitro group and the azide group in o-nitrophenylazide induced by the TiCl4/Sm system: a novel synthesis of 2,3-dihydro-1H-1,5-benzodiazepines

o-Nitrophenylazide was treated with the low-valent titanium reagent derived from the TiCl4/Sm system to produce the intermediate 2 in situ, which was a ‘living’ double-anion and reacted readily with ketones containing active methyl or methylene groups to afford 2,3-dihydro-1H-1,5-benzodiazepines in moderate to high yields under mild and neutral conditions.