This work involves synthesis of different five and six membered heterocyclic rings starting from oxalic acid and divided into four different parts and the reaction steps for each part are summarized as shown below. First part: This part involved the synthesis of pyridazin ,phthalazin, pyrazole ,pyrazolone and triazole derived from oxalic acid hydrazide .Scheme (I). Second part:This part involved the synthesis of thiazolidine,triazole,thiadiazole,and ?4-oxazoline derivatives via the cyclization of substituted semicarbazide and substituted thiosemicarbazide with p-phenylphenacyl bromide ,2N NaOH and sulfuric acid respectively. The substituted semicarbazide and substituted thiosemicarbazide were synthesized through the reaction of oxalic acid hydrazide with phenyl isocyanate and phenyl isothiocyanate .(SchemeII). Third part: This part involved the synthesis of 1,3,4-oxadiazole and oxazepine derivatives from oxalic acid hydrazide. (Scheme III). Fourth part: This part deals with the evaluation of antibacterial activities of some of the synthesized compounds and comparing these activities with that of the starting materials. These activities were determined in vitro using disc diffusion method against two pathogenic strains of bacteria (Escherichia Coli and Staphylococcus aureus), the results revealed that some of these compounds showed measurable activity.
Scheme (I)
Scheme (II)
Scheme (III)