الفهرس 
Acetylation of 4Only 14 pages are availabe for public view
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Abstract
This work illustrates the versatile role of β-enaminonitriles and β-enaminoesters moieties in the synthesis of different heterocyclic systems and new thienopyrimidine derivatives from readily obtainable materials.
The work can be divided into three main parts:-
i- First part deals with β-enaminonitriles
ii- Second part deals with β-enaminoesters
iii- Third part deals with chemical behaviour of pyridothienooxazinone towards different nucleophiles
First part: synthesis and reactions of β-enaminonitriles.
Thus, the target compound, 3-amino-5-bromo-4,6-dimethylthieno[2,3-b]pyridine-2-carbonitrile (4) was constructed by cyclization of the nicotinonitrile 3 by ethanolic sodium ethoxide solution. Pyridine derivative 3 was obtained by treatment of the thione derivative 2 with chloro-acetonitrile in refluxing absolute ethanol containing fused anhydrous sodium acetate. Thiation of pyridone 1 under the effect of phosphorous pentasulfide in dry toluene afforded the thione 2 [cf.scheme 1].
The chemical behaviour of the starting β-enaminonitrile 4 towards different carbon electrophiles had been studied. Thus the hitherto unknown 4 reacted with p-anisaldehyde, freshly distilled acetic anhydride and/or phenyl isothiocyanate to afford the Schiff base 6, a mixture of mono- & diacetyl derivatives 7, 8 and thiourea derivative 9 respectively. Furthermore, diacetyl-amino derivative 8 was authentically prepared by acetylating the monoacetylamino derivative 7 using freshly distilled acetic anhydride [cf. scheme 1].