Synthesis of novel substituted naphthoquino[b]-benzo[e][1,4]diazepines via Pictet–Spengler cyclization

Synthesis of novel 4,5-dihydro-1H-1,4-naphthoquino[b]-benzo[e][1,4]diazepine derivatives via Pictet–Spengler cyclization is reported. Reaction of 2,3-diamino-naphthoquinones with aldehydes in the presence of BF3·Et2O gives benzodiazepine-naphthoquinones in good yields.