Microwave-induced CAN promoted atom-economic synthesis of 1H-benzo[b]xanthene and 4H-benzo[g]chromene derivatives of N-allyl quinolone and their antimicrobial activity

Some new 1H-benzob]xanthene and 4H-benzog]chromene derivatives of N-allyl quinolone were efficiently synthesized via microwave-induced one-pot three component reaction of N-allyl quinolones, 2-hydroxy-1,4-naphthoquinone and cyclic β-diketones/malononitrile, and iso-propylcyanoacetate in the presence of catalytic amount of ceric ammonium nitrate under solvent-free condition. This methodology allowed us to achieve the desired products in excellent yields in a very short time without the use of solvent. The % atom economy was calculated for all the newly synthesized compounds and found in the range of 92–96 %. Titled derivatives were elucidated by ¹H NMR, ¹³C NMR, FT-IR, elemental analysis, and mass spectral data as well as tested against a panel of pathogenic strains of bacteria and fungi using by microdilution minimum inhibitory concentration method. The structural activity relationship analysis demonstrated that electronic influence and lipophilicity of different groups make much difference in the antimicrobial potency.