L-Proline catalyzed domino cyclization for the green synthesis of novel 1,4-dihydrobenzo[a]pyrido[2,3-c]phenazines

摘要

l-Proline has been used as an efficient, reusable, and bifunctional organocatalyst for the one-pot, two-step, five-component synthesis of novel 1,4-dihydrobenzo[a]pyrido[2,3-c]phenazines by the condensation reaction of 2-hydroxynaphthalene-1,4-dione, aromatic 1,2-diamines, aldehydes, ammonium acetate, and ethyl acetoacetate under conventional heating in solvent-free conditions. In this domino transformation, six bonds and two new rings are efficiently formed. High yields, short reaction time (20-30 min), operational simplicity, easy work-up procedure, avoidance of hazardous or toxic catalysts and organic solvents are the main advantages of this green methodology.