Synthesis of tetracyclic pyrido-fused dibenzodiazepines via a catalyst-free cascade reaction.

An efficient, eco-friendly protocol has been described for the chemoselective synthesis of tetracyclic pyrido-fused dibenzodiazepines derivatives via catalyst-free, three-component reaction of dimedone, 1,2-diamines, 3-formylchromones, and malononitrile. The significant advantages of this cascade approach are to create two new rings and four new σ bonds containing three C-N and one C-C bond, as well as the breakdown of a C-O bond.