الفهرس 
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Abstract
This work illustrates the versatile role of 2(1H)-pyridone moiety in the synthesis of different heterocyclic systems from readily obtainable materials.
The work can be divided into three main parts: -
i- Synthetic utility and chemical behaviour of 2-pyridone derivative.
ii- Synthetic utility and chemical behaviour of 2-chloro -quinoline derivative.
iii- Synthetic utility and chemical behaviour of 5-bromo-2-chloro-4,6-dimethylnicotinonitrile.
First part: Synthetic utility and chemical behaviour of 2-pyridone derivative.
Substituted 2-pyridones 1, 2 and 3 have been synthesized via one-pot multi-component reactions of an acetonitrile derivative (cyanoacetic ester, or cyanoacetamide) with heteroaromatic or aromatic aldehyde and a cyclic ketone in the presence of a basic catalyst in alcohol heated to its refluxing temperature. Reaction of compound 2 with ethyl chloroacetate in dry acetone in presence of anhydrous potassium carbonate afforded oxygen alkyl product 4. [cf. scheme I].
Scheme I
Second part: Synthetic utility and chemical behaviour of 2-chloroquinoline derivative.
Chlorination of compound 1 with phosphorous oxychloride afforded the corresponding 2-chlorotetrahydroquinoline 5. The reactivity of 2-chlorotetrahydroquinoline-3-carbonitrile 5 towards some nucleophilic reagents namely, sodium azide, thiosemicarbazide, morpholine and hydrazine hydrate has been investigated and tetrahydrotetrazolo[1,5-a]quinoline 6, fused
hexahydrotriazoloquinoline 7, tetrahydroquinoline derivative 8 and 2-hydrazinyl-tetrahydroquinoline derivative 9, have been obtained
respectively. Formylation of the latter compound with formic acid and / or formamide afforded N-formyl derivative 10. Benzoylation and acetylation of 2-hydrazinylbenzothiazinone 9 by benzoyl chloride and acetic anhydride afforded benzohydrazide derivative 11 and diacetyl derivative 12, respectively [cf. scheme II].
Scheme II
Thiation of 2-pyridone 1 by phosphorous pentasulfide in dry toluene yielded thione derivative 13 which was also obtained from other way via reaction of chloro derivative 5 with thiourea in ethanol. Methylation of thione derivative 13 gave the corresponding S-methyl derivative 14. The reaction of thione derivative 13 with ethyl chloroacetate, chloroacetyl chloride and / or chloroacetonitrile in presence of fused anhydrous sodium acetate in refluxing ethanol afforded the S-alkyl derivatives 15-17. Cyclization of compound 17 with aqueous ethanolic sodium hydroxide afforded tetrahydrothieno[2,3-b]quinoline derivative 18 [cf. scheme III].
Scheme III
Third part: Synthetic utility and chemical behaviour of 5-bromo-2-chloro-4,6-dimethylnicotinonitrile.
Enaminonitrile derivative 20 was obtained via amination of chloropyridine derivative 19 with ammonium acetate. Condensation of enaminonitrile derivative 20 with 4-methoxybenzaldehyde afforded Schiff base derivative 21. Effect of nitrogen nucleophiles on enaminonitrile derivative 20 namely, phenylhydrazine and hydroxylamine hydrochloride have been investigated to afford nicotinonitrile derivatives 22 and 23. Reaction of bidentate nucleophilic reagents namely, ethylenediamine, ethanolamine and / or propanolamine in refluxing ethanol afforded nicotinonitrile derivatives 24-26, respectively. Hydrolysis of cyano functionality has been investigated via reaction of compound 19 with sulfuric acid (70%) to give the corresponding amide derivative 27 [cf. scheme IV].
Scheme IV