Synthesis of some new 4-[P-heterocyclo-substituted aniline] -2,7-dimethyl-l,8-naphthyridines of expected antimicrobial activity

ABSTRACT

The reaction of 4-chloro-2,7-dimethyl-l,8-naphthyridine [1] with benzocaine and/or aminophenol gives the corresponding ethyl naphthyridineaminobenzoate derivative 2a and/or p-hydroxy-anilinonaphthyridine derivative 2b depending upon the nature of the reactants used. The reaction of compound 2a with hydrazine hydrate gives the corresponding acid hydrazide 3 which was allowed to react with CS[2] at different conditions giving the oxadiazole 4 and / or the dithiocarbazate 5, and with a beta-diketone and a [3-dikctoester to give the corresponding pyrazole 9 and/or the pyrazolone 10. As well as, the reaction of the acid hydrazide 3 with different aromatic aldehydes afforded the Schiff bases 11a-d. which upon cyclization with thioglycolic acid afforded the thiazolidinones 12. On the other hand, the reaction of 1 with different amines, afforded 4-substituted 1,8-naphthyridines 13a-c, which gave the 2,7- distyrylnaphthyridines 14a-d upon reaction with different aromatic aldehydes. Moreover, reaction of 1 with p-hydroxy- acetophenone and/or p-aminophenol gave the corresponding 4-[p-acetylphenoxy] and/or 4-[p-aminophenoxy]-1,8-naphthyndine derivatives 15a and/or 15b, respectively. Reaction of 15a with different aldehydes afforded the chalcones 16a-d, 2-[lH] oxopyridines 17a-f, 2-[lH]iminopyndmes 19a,b, 2-[lH] thioxopyndincs 20a-c, while reaction of 15b with aromatic aldehydes gave the 1,8-naphthyridine-p-phenoxy Schiff bases 21a-c and other related compounds have been synthesized. Furthermore, some 1,8-naphthyridine Mannich bases 24a-d were produced by treatment of 2b with p-formaldchyde and secondary amines. In addition, reaction of 4 with ethanolic solution of paraformaldehyde and the appropriate secondary amine, afforded the corresponding 1,3,4-oxadiazole Mannich bases 25a-c. Some of the new compounds were evaluated for their antimicrobial activity