الفهرس 
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Abstract
As one of the main goals of present thesis, quinazoline synthesis permits
an easy synthetic entry to a class of 1, 2, 4-triazoles based substituted
quinazoline and 1, 2, 3-triazole-N-glycoides based quinazoline structure.
The 1, 3-dipolar cycloaddition strategy was employed to create the 1, 2,
3-triazole core structure through click-reaction in the targeted molecules.
N-substituted quinazolinethione compounds (2-4) were synthesized by
reaction with aseries of isothiocyanate derivatives and 2-aminobenzoic
acid (1) in ethanol was refluxed in the presence of triethylamine for 5 h.
N-substituted quinazolinethione derivatives (2-4) with hydrazine hydrate
afforded the corresponding 2-hydrazinyl derivatives (5-7) The formed
hydrazinyl quinazoline derivatives were then allowed to react with carbon
disulfide in basic medium and the 4-substituted-1-mercapto-
[1,2,4]triazolo[4,3-a] quinazolin-5(4H)-one derivatives (8,9) resulted in
good yields.
The terminal acetylenic derivatives (12, 13) of the quinazolyl thio acetic
acid (10, 11) derivatives were synthesized via thioalkylation of the
starting quinazoline-thiol (3, 4) by reaction with chloroacetic acid in
dryDMF and the prescnce of anhydrous potassium carbonate with
continuous stirring for 36 h at 100°C followed by esterification reaction
with propargyl alcohol in 30 ml of absolute ethanol and 1ml of sulfuric
acid at 80°C for 36 hours while stirring constantly.
The sulfanyl-substituted ester derivatives (14, 15) formed by
esterification of the starting quinazoline thoil (3, 4) in dry DMF with
ethyl chloroacetate in the presence of an anhydrous potassium carbonate
following a 24-hour stirring period at 70 °C. compounds (14,15) were
converted to the corresponding 4-substituted-1-hydrazinyl-[1,2,4]
triazolo[4,3-a]quinazolin-5(4H)-one (16,17) via reaction with
thiosemicarbzide in absolute methanol ,mixed with 20 ml of sodium
methoxide and then acidified with HCl. The sulfanyl-aceto hydrazide (18,
19) was prepared from the compounds (14, 15) according to the reaction
with hydrazine hydrate (80%) in absolute ethanol after stirring the
mixture for 24hr at room temperature.
The sulfanyl-aceto hydrazide (18, 19) was found a useful key structure
for the synthesis of functionalized bicyclic compounds. Thus, reacting
ethyl cyanoacetate and malononitrile with the acetyl hydrazides (18, 19)
in presence of para-chlorobenzaldehyde in absolute ethanol afforded the
bicyclic structural products of the quinazolyl-triazolopyridine hybrid
products incorporating aryl substituents.