Revisited synthesis of fused diazepines from 3-(3-aryl-3-oxopropenyl)chromen-4-ones and binucleophilic amino enones in a three-step domino process

The synthesis of tetracyclic 11,12,13,14b-tetrahydrodi-benzo[b,f]pyrido[1,2-d][1,4]diazepines was revisited via a catalyst-free three-step domino reaction involving a pyrone ring-opening/aza-Michael addition/intramolecular cyclization, the reactants having been o-arylenediamine-dimedone adducts and 3-(3-aryl-3-oxopropenyl)chromen-4-ones. The 3-positioned exocyclic a,b-enone fragment on the chromone moiety is involved in the cyclization into the final products at the last step of the process.