Abstract
Common and novel synthesized active methylene compounds as well as heterocycles bearing active methyl or having an active methine were used in the syntheses of a wide variety of substituted and fused five-, six- and seven-membered nitrogenous heterocyclic systems of interesting medical and pharmaceutical importance such as triazoles, pyridazines, triazines, and diazepines. Carbothiosemicarbazides, carbothiohydrazones and 2-hydrazinoazaherterocycles were used as suitable starting materials for triazole formation. The preparation of tetrazoles showed a valence ring-chain tautomerism. The key starting materials for the synthesis of pyridazines were acetohydrazide derivative, activated enones, enaminones, and aryl hydrazones. The reaction of 2-chloro or 2-hydrazinoazaheterocycles and thiocarbohydrazones with different reagents under suitable reaction conditions led to the formation of triazines. Diazepines were obtained via treatment of enones with 1,2-diamino derivatives. Also, the antimicrobial activities of some selected synthesized heterocyclic compounds were reported.