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Abstract
A Several novel 2,3-dihydroquinazolin-4(1H)-ones bearing either chalcone , pyrazole or thiazole moieties have been synthesized with a survey of their analgesic and anti-inflammatory activities. In addition, novel 3,4-dihydro-1H-benzo[e][1,2,4]triazepin-5(2H)-ones have been synthesized with a survey of their C.N.S. activities.
The starting material in this investigation was anthranilic acid (I) which was utilized to obtain the key intermediates N-alkyl isatoic anhydrides (IIIa,b) via its reaction with either dimethylsulphate or ethyl iodide in aqueous sodium carbonate solution to give the alkylated product II a,b which were then cyclized under the effect of ethylchloroformate.
To obtain the target 2,3-dihydroquinazolin-4(1H)-ones, the following routes were followed:
1- Refluxing N-alkyl isatoic anhydride (IIIa,b) with p- amino acetophenone in glacial acetic acid for 4 hours afforded the intermediate N- (4-acetylphenyl) -2- (alkylamino) benzamides (IVa,b).
2- Cyclization of intermediates IVa,b was achieved using formalin in ethanol containing catalytic amount of acetic acid to form the 2,3-dihydroquinazolin-4(1H)-one derivatives Va,b.3-Condensation of Va,b with aromatic aldehyde was conducted in methanol in the presence of sodium hydroxide to yield the desired chalcones VIa-h.
4- Cyclization of chalcones VIa-d was performed using either hydrazine hydrate or phenyl hydrazine to afford the novel 4,5-dihydro-1H-pyrazoles VIIa-d or their N-phenyl analogs VIIe-h .
5- Condensation of compound Va with thiosemicarbazide was achieved in ethanol containing catalytic amount of acetic acid to obtain the novel hydrazinecarbothioamide VIII intermediate.
6- The hydrazinecarbothioamide intermediate VIII was cyclized using phenacyl bromides in refluxing ethanol with further addition of anhydrous sodium acetate to afford the novel thiazole containing compounds IXa,b.