Regioselective multicomponent domino reactions providing rapid and efficient routes to fused acridines

Regioselective three-component reactions of aromatic aldehydes with indazol-5-amine and 2-hydroxy-1,4-naphthoquinone in HOAc under microwave irradiation have been developed. In this one-pot reaction, a series of new pyrazole-fused benzo[h]acridine derivatives with 1,2-diketone unit were synthesized with high chemical yields. The resulting pyrazole-fused acridines were employed to further react with aldehydes and ammonium acetate to give polycyclic oxazole-fused pyrazolo[3,4-j]acridines. The present green synthesis shows several advantages including operational simplicity and fast reaction rates, which makes it a useful and attractive process of library generation for drug discovery.