An efficient synthesis of novel spiro[benzo[c]pyrano[3,2-a]phenazines] via domino multi-component reactions using l-proline as a bifunctional organocatalyst

A novel, domino, multi-component reaction for the synthesis of polyfunctionalized spiro[benzo[c]pyrano[3,2-a]phenazine] derivatives has been established. l-Proline has been used as a bifunctional catalyst for the one-pot condensation of 2-hydroxy-1,4-naphthoquinone with aromatic 1,2-diamines to form the corresponding quinoxalines and then cyclo-condensation with an alkylmalonate and a cyclic carbonyl compound leads to novel spiro[benzo[c]pyrano[3,2-a]phenazine] derivatives in high yields and short reaction times.