الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
PART I: Part (I) : Synthesis of some new 4-arylidene-5 (4H)-oxazolone derivatives and their cytotoxicity to human cancer cell lines Condensation of p-aminohippuric acid (1) with different substituted aromatic aldehydes 2 yielded the corresponding 4-(arylideneamino-benzoyl)-glycine derivatives 3a-e formation of 2-(4-arylideneamino)-phenyl)-4-(4-methoxy-benzylidene)-oxazol-5(4H)-ones 4a-e were achieved by classical Erlenmeyer reaction, involving condensation of compounds 3a-e with p-anisaldehyde in presence of acetic anhydride and sodium acetate under heating condition at 100°C . 4-[(2-amino-4-phenylthiazol-5-yl)azo]benzoyl-glycine (14) was synthesized in good yield (%80) by diazotization of 1 with sodium nitrite at 0-5°C and hydrochloric acid followed by diazocoupling with 2-amino-4-phenyl-thiazole (13) in ethanol buffered by sodium acetate solution. The formation of 2-[4-(2-acetylamino-4-phenylthiazol-5-yl)azo-phenyl]-4-benzylidene-oxazol-5(4H)-one (15) was synthesized by condensation of 5-arylazothiazole compound 14 with benzaldehyde in presence of acetic anhydride and sodium acetate under refluxing condition at 100 °C. Hetero-cyclization of cyanoacetamide derivative 20 into our target oxazole was achieved by condensation with p-anisaldehyde in presence of acetic anhydride and sodium acetate under refluxing condition at 100 °C to furnish 2-[4-(2-cyanoacetamido)phenyl]-4-(4-methoxybenzylidene)- oxazol-5(4H)-one (21) In addition, 4-[2-cyano-3-(4-methoxyphenyl)-acrylamido]benzoyl-glycine 22 has been formed by condensation of compound 20 with p-anisaldehyde by heating under reflux in ethanol containing drops of piperidine. Moreover, 2-[4-(2-cyano-3-(4-methoxyphenyl)acrylamido)-phenyl]-4-(4-methylbenzylidene)-oxazol-5(4H)-one (23) was synthesized by classical Erlenmeyer reaction, involving condensation of compound 22 with p-tolualdehyde in presence of acetic anhydride and sodium acetate under refluxingThe reactivity of methylene group of cyanoacetamide derivative 20 has been examined towards electrophilic diazcoupling reaction. Thus, diazocoupling reaction of cyanoacetamide derivative 20 with p-tolyl diazonium chloride at 0-5°C in ethanol buffered with sodium acetate solution furnished 4-[2-cyano-2-(4-tolylhydrazono)-acetamido]-benzoyl-glycine (24). Finally, synthesis of 2-[4-(2-cyano-(4-tolylhydrazono)-acetamido)-phenyl]-4-(4-methoxy-benzylidene)-oxazol-5(4H)-one (25) were achieved by classical Erlenmeyer reaction, involving condensation of compound 24 with p-anisaldehyde in presence of acetic anhydride and sodium acetate under refluxing condition at 100 °C. Part (II): Synthesis some new benzoxazole derivatives and their cytotoxicity to human cancer cell lines N-(4-Acetamidophenyl)-2-(benzoxazol-2-ylthio)-acetamide (27) is formed by treatment of 2-mercaptobenzoxazole with p-(N-chloroacetyl-amino)-acetanilide (26) in ethanol and sodium acetate under reflux. 2-(Benzoxazol-2-ylthio)-N-(4-substituted-5-phenylazo-thiazol-2-yl)-acetamide derivatives 29 were synthesized by the reaction of 5-phenylazo-2-(chloroacetylamino)-thiazole derivatives 28 with 2-mercaptobenzoxazole in hot ethanol containing catalytic amount of trimethylamine N,N’-(Diselanediyl-bis(2-methoxy-4,1-phenylene))-bis(2-(benzo-xazol-2-ylthio)-acetamide) (31) has been obtained when 2-mercapto-benzoxazole was treated with N,N’-(diselanediylbis(2-methoxy-4,1-phenylene))bis-(2-chloro-acetamide) (30) in ethanol and sodium acetate under reflux The synthesis of 2-hydrazinylbenzoxazole (35) is reported in the literature by treatment 2-mercaptobenzoxazole with hydrazine hydrate in ethanol under reflux. Heating of 2-hydrazinylbenzoxazole (35) with ninhydrin under reflux in ethanol and DMF mixture furnished the corresponding condensation product 2-(2-(benzoxazol-2-yl)hydrazono)-1H-indene-1,3(2H)–dione (36). Finally, condensation of 2-hydrazinylbenzoxazole (35) with piperonal was achieved by heating in ethanol containing 0.5 ml acetic acid to afford the corresponding 2-(2-(benzo[d][1,3]dioxol-5-ylmethylene)-hydrazinyl)benzoxazole (37). Part (III): In Vitro Antitumor Activity: Oxazole and benzoxazole compounds 4a-e, 6, 8, 12, 15, 18, 21, 23, 25, 27, 29, 31, 36 and 37 were evaluated for their effects on the viability of various human cancer cell lines: HepG2 (hepatocellular carcinoma), HTC-116 (colorectal carcinoma), PC-3 (human prostate cancer carcinoma) and MCF-7 (mammary gland breast cancer). Our results indicate that the synthesized benzoxazole derivatives exhibit moderate to strong cytotoxic effects toward the four tested human cancer cell lines.