2012-02-12

The thesis includes several pathways: The first pathway is dedicated to the synthesis of protected dipeptides hydrazide protected amino acids (S17-S25) are prepared by the reaction of p-toluene sulphonyl chloride or benzoyl chloride with amino acids (glycine, valine, alanine, leucine, and isoleucine). Then protected dipeptide esters (S26-S42) is prepared by the reaction of compounds (S17-S25) with dicyclohexylcarbodiamide(as coupling reagent) and amino acid esters(S9-S16) (which they were prepared through passing hydro- chloric acid gas to the suspension of amino acid in ethanol to obtained amino acid esters hydrochloric acid (S1-S8) and then passed ammonia gas through the suspension of compounds (S1-S8) in dichloromethane) .There after hydrazides (S48-S62) are obtained by the reaction of corresponding esters (S26-S42) with hydrazine hydrate. Where the second path involves synthesis of five and six membered ring heterocyclic compounds.Hydrazones (S68-S77) are synthesized by the reaction of the above hydrazides with p-nitro benzaldehyde , which was cyclized to 2,5- disubstituted 1,3,4- oxadiazole (S80-S89) through lead oxide and to phthalazines (S99-S100) through hydrochloric acid. 1,3,4- oxadiazole -2- thione (S92-S98) were prepared by the reaction of the corresponding hydrazides with carbon disulfide in alcoholic potassium hydroxide. Hydrazides were reacted with ammonium thio cyanate to afford thiosemicarbazide (S102-S104) which were cyclized to 1,2,4- triazole -3- thione (S105-S106) in potassium hydroxide medium.