الفهرس 
Chemistry of quinazolineOnly 14 pages are availabe for public view
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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 derived 2-hydrazinyl products(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 sulfanyl-substituted ester derivatives (10, 11) formed by
esterification of the starting quinazoline thoil (2,3) in dry DMF with ethyl
chloroacetate in the presence of and anhydrous potassium carbonate
Following a 24-hour stirring period at 70 °C. compounds (12,13) were
converted to the corresponding 4-substituted-1-hydrazinyl-[1,2,4]
triazolo[4,3-a]quinazolin-5(4H)-one (12,13) via reaction with
thiosemicarbzide in absolute methanol ,mixed with 20 ml of sodium
methoxide and then acidified with HCl. The sulfanyl-aceto hydrazide (14,
15) was prepared from the compounds (10, 11) according to the reaction
with hydrazine hydrate (80%) in absolute ethanol after stirring the
mixture for 24hr at room temperature
The sulfanyl-aceto hydrazide (14, 15) was found a useful key structure
for the synthesis of functionalized bicyclic compounds. Thus, reacting
ethyl cyanoacetate and malononitrile with the acetyl hydrazides (12, 13)
in presence of para-chlorobenzaldehyde in absolute ethanol afforded the
bicyclic structural products of the quinazolyl-triazolopyridine hybrid
products incorporating aryl substituents
The terminal acetylenic derivative (22, 23) of the quinazolyl thio acetic
acid (20, 21) derivative was synthesized via thioalkylation of the starting
quinazoline-thiol (2, 3) by reaction with chloroacetic acid in dryDMFand
the prescnce of anhydrous potassium carbonate with continuous stirring
was for 36 h at 100 °C t 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 crucial acetylenic terminal active center compounds (24, 25) were
produced through the interaction of quinazoline-thiols (2, 4) were
dissolved in (H2O + EtOH; (1 :2 ) (20ml) in an alkaline environment anhydrous potassium hydroxide) with stirring for about 20 minutes in an
ice bath. Propargyl bromide was added dropwise and stirring was
continued for 7h.