الفهرس 
Chemistry of 1,3-thiazines and BenzothiazinesOnly 14 pages are availabe for public view
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Abstract
The current work illustrates the versatile role of 2-thioxobenzothiazinone moiety in the synthesis of different heterocyclic systems from simple readily obtainable materials.
The work can be divided into four main parts:-
i- Synthesis of 2-thioxobenzothiazinone and its reactions
ii- Synthetic utility and chemical behaviour of 2-hydrazinylbenzothiazinone derivative
iii- Synthetic utility and chemical behaviour of 2-(methylthio)-benzothiazinone
iv- Study of biological activity of some synthesized compounds
First part: Synthesis of 2-thioxobenzothiazinone and its reactions
2-Thioxo-1,2-dihydrobenzo[d][1,3]thiazin-4-one (1) and 1H-benzo[d][1,3]thiazine-2,4-dithione (2) have been synthesized via reaction of anthranilic acid and carbon disulfide (5 mL and / or 10 mL) in alcoholic potassium hydroxide heated to its refluxing temperature, respectively.
The reactivity of benzothiazinone 1 towards some nucleophilic reagents namely, hydrazine hydrates and ammonium solution has been investigated and 2-hydrazinylbenzothiazinone derivative 3, and 2-aminoquinazolinone 4, have been obtained respectively. On the other hand the reactivity of benzothiazinone 1 towards some electrophilic reagents namely, methyl iodide in presence of potassium hydroxide and benzyl chloride in acetone containing anhydrous potassium carbonate has been investigated and S-methylated 5, and S-benzylated derivative 6 have been obtained respectively. Benzothiazinone derivative 7 have been formed via Mannich reaction of benzothiazinone 1 with p-anisidine and formaldehyde in presence of a catalytic amount of concentrated hydrochloric acid [cf. scheme I].
Scheme I
Second part: Synthetic utility and chemical behaviour of 2-hydrazinylbenzothiazinone derivative 3
Heating 2-hydrazinylbenzothiazinone derivative 3 with fomamide, formic acid and/ or glacial acetic acid at refluxing temperature afforded benzotriazolothiazinone derivative 8, formyl derivative 9 and benzotriazolothiazinone derivative 10, respectively. Treatment of hydrazinylbenzothiazinone derivative 3 with acetylacetone in ethanol gave benzothiazinone derivative 11.
Pyrazolone derivative 12 and pyrazolidindione derivative 13 have been formed via reaction of 2-hydrazinylbenzothiazinone derivative 3 with ethyl cyanoacetate in refluxing ethanol and diethylmalonate at 180 °C, respectively.
Condensation of 2-hydrazinylbenzothiazinone derivative 3 with anhydrides namely, maleic and tetrachlorophthalic anhydrides in boiling dioxane yielded benzothiazinylpyridazine 14a and phthalazindione derivative 14b [cf. scheme II].