Synthesis and H1-Antihistaminic Activity of Some Novel 1-Substituted-4-(3-methylphenyl)-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones

Reactivity of 2-ethoxyquinazolin- 4-yl hydrazine and its use in synthesis of novel quinazoline derivatives of antimicrobial activity

The reactions of 2-ethoxy-4-hydrazinoquinazoline 2 with diethyl oxalate and ethyl chloroacetate gave 6-ethoxy-2H-[1,2,4]triazino[4,3-c]quinazoline-3,4-dione 3 and 6-ethoxy-2,3-dihydro-4H-[1,2,4]triazino[4,3-c]quinazolin-4-one 4 respectively. A series of 5-ethoxy-2-X-[1,2,4]triazolo[1, 5-c]quinazolines 5a-d was also produced by reacting 2 with the acid chlorides namely: benzoyl, crotonyl, cinnamyl and 2-furoyl chlorides via Dimroth rearrangement. Also, 2 reacted with ethyl chloroformate giving 6. Condensation of 2 with acetone gave Schiff base 7, and with monosaccharides gave the sugar hydrazones 8a-e which were thereafter acetylated giving the corresponding 9a-e. Cyclization of 8a-e by iron(III) chloride gave triazoloquinazolines 10a-e acyclic C-nucleosides which, by acetylation, afforded 11a-e. All products were confirmed by elemental, IR, MS, and 1H-NMR analysis. Products 8-11 were chosen for biological screening test against gram(+ ive) and gram(- ive) bacteria.

Anticonvulsant Activity of Schiff Bases of 3-Amino-6,8-dibromo-2-phenyl-quinazolin-4(3H)-ones

Schiff bases (9a-l) of 3-amino-6,8-dibromo-2-phenyl-quinazolin-4-(3H)-ones (8) with various substituted aldehydes were obtained by refluxing 1:1 molar equivalents of the reactants in dry ethanol for 6 h. The aminoquinazoline (8) was inturn obtained from 3,5-dibromoantharlinic acid via intermediate (7). All the synthesized compounds (9a-l) were evaluated for their anticonvulsant activity on albino mice by maximal electroshock method using phenytoin as a standard. The compound (9l) bearing a cinnamyl function displays a very high activity (82.74 %) at dose level of 100 mg/kg b.w.

Synthesis of acyclo C-Nucleosides of H1-antihistaminic 4-substituted [1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones

Two series of aldose N-(3-substituted-4-oxo-3,4-dihydroquinazolin-2-yl)hydrazones were prepared by the reaction of each of the aldoses with the appropriate 2-hydrazino-3-substituted-quinazolin-4(3H)-ones. Oxidative cyclisation of these aldose hydrazones with ferric chloride in ethanol yielded the title acyclo C-nucleosides.