An efficient and simple method for the synthesis of biologically
interesting benzo[a]pyrano[2,3-c]phenazines by a four-component
reaction of o-phenylenediamines, 2-hydroxynaphthalene-1,4-dione,
isocyanides, and dialkyl acetylenedicarboxylates in N,N-dimethylformamide
at 100 ˚C is reported.
isocyanide - benzo[a]pyrano[2,3-c]phenazine - dialkyl acetylenedicarboxylates - phenazine - phenylenediamines