Synthesis and antimicrobial evaluation of some alkoxyphthalimide derivatives of naphthyridine

5-(4-Substitutedphenyl)-8,8-dimethyl-5,8,9,10-tetrahydrobenzo[b][1,8]naphthyridin-7H-one 1a-e have been converted to their N-substituted alkoxyphthalamide derivatives using two alternative pathways. In route one, 1a-e are treated with formalin (37%) to yield 5-(4-substitutedphenyl)-10-(hydroxymethyl)-8,8-dimethyl-5,8,9,10-tetrahydrobenzo[b][1,8]naphthyriding-6-7H-one 2a-e, which is further changed to corresponding chloro derivatives 3a-e by the treatment with thionyl chloride. Condensation of 3a-e with N-hydroxyphthalimide furnished the final compounds 2-{[5-(4-substitutedphenyl)-8,8-dimethyl-6-oxo-6,7,8,9-tetrahydrobenzo[b][1,8]naphthyridin-10-5H-yl]mehtoxy}phthalimide 4a-e. In another route, 1a-e is directly condensed with omega-bromoalkoxyphthalimide to yield Higher homologues of 4a-e i.e. 2-{2-[5-(4-substituted phenyl)-8,8-dimethyl-6-oxo-6,7,8,9-tetrahydrobenzo[b][1,8]naphthyriding-10-5H-yl]ehtody} phthalimide derivatives 5a-e. Structures of all the synthesized compounds have been established on the basis of elemental analysis and spectral studies. All the synthesized compounds have been screened for antibacterial and antifungal activities.