A rapid, efficient, and green synthesis of benzo[$a$]chromeno[2,3-$c$]phenazine derivatives via microwave assistance and DABCO~catalyzed a novel domino cyclization

An efficient, convenient, and environmentally benign procedure for the synthesis of novel benzo[$a$]chromeno[2,3-$c$]phenazine derivatives has been developed by domino four-component condensation reaction between 2-hydroxynaphtha- lene-1,4-dione, $o-$phenylenediamine, aromatic aldehydes, and naphthols or phenol in the presence of a catalytic amount of DABCO as an expedient, ecofriendly, and reusable base catalyst under microwave irradiation in EtOH/H$_{2}$O (1:1). This green process produces biologically and pharmacologically significant heterocycles in a single one-pot operation and offers considerable advantages such as operational simplicity, short reaction time, high yields, reusability of the catalyst, absence of any tedious workup or purification, and avoidance of hazardous reagents/solvents.