One-Pot, Sequential Four-Component Synthesis of Benzo[a]chromeno[2,3-c]phenazine Derivatives Using SiO2–SO3H as an Efficient and Recoverable Catalyst Under Conventional Heating and Microwave Irradiation

Abstract

ABSTRACTSilica sulfuric acid (SiO2–SO3H) has been used as an effective and reusable solid catalyst for the one-pot, two-step, four-component microwave-assisted synthesis of benzo[a]chromeno[2,3-c]phenazine derivatives by the condensation reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aldehydes, and cyclic 1,3-dicarbonyl compounds. This new procedure has a number of advantages such as: high yields, very short reaction time, operational simplicity, simple work-up procedures and avoidance of hazardous or toxic catalysts, and organic solvents and is devoid of inessential derivatization and generation of hazardous substances. Moreover, the catalyst shows high thermal stability and can be recovered and reused without loss of reactivity.