- Enaminones as building blocks in heterocyclic synthesis: New syntheses of nicotinic acid and thienopyridine derivatives
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Reacting 1,3-diphenyl-propan-2-one with equimolecular amount of dimethylformamide dimethylacetal afforded the enaminone 4. This when reacted with another equimolecular amount of dimethylformamide dimethylacetal afforded the dienaminone 5. Compound 4 condenses with cyanothioacetamide and with cyanoacetamide to yield 2-thioxo- and 2-oxo-pyridine-3-carbonitrile derivatives 6a,b respectively. Compound 6a reacted with (x-chloroacetone 8 to yield the thieno[2,3-b]pyridine derivative 10 that cyclized further into 4,7,8-trisubstituted pyrido[2′,3′:2,3] thieno[4,5-d]pyrimidine 12. Compound 4 also afforded 2,5,6-trisubstituted nicotinic acid ethyl ester 13 by reaction with ethyl acetoacetate in acetic acid in the presence of ammonium acetate. The dienaminone 5 reacted with acetic acid, ammonium acetate/acetic acid, phenylhydrazine and 5-amino-3-methylpyrazole yielding 3,5-diphenyl-pyran- 4-one 15a, 3,5-diphenyl-1H-pyridin-4-one 15b and 1,3,5-trisubstituted pyridin-4-ones 16a-b.
- Abdelkhalik, Mervat Mohammed,Eltoukhy, Afaf Mohammed,Agamy, Samia Michel,Elnagdi, Mohammed Hilmy
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p. 431 - 434
(2007/10/03)
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- Vilsmeier-Haack reactions of carbonyl compounds: Synthesis of substituted pyrones and pyridines
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Vilsmeier-Haack reaction of substituted phenylacetones leads to the formation of conjugated iminium salts which on aqueous basic work up afford 3-formyl-4-pyrones and on ammonium acetate-induced cyclization afford 5-aryl-4-chloronicotinaldehydes in good y
- Thomas, Ajith Dain,Josemin,Asokan
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p. 5069 - 5076
(2007/10/03)
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- Oxidative Rearrangement of α-Benzylideneketones with Thallium(III) Nitrate in Methanol
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Sterically unhindered arylidene- and diarylideneacetones 1 or 2 having electron releasing aryl groups yielded with thallium(III) nitrate in methanol β-ketoacetals 3, 4 and 5, respectively.Electronegatively substituted 1f and sterically hindered 1g and 1h gave the 4-arylcrotonic esters 7 and by-products, while 1,3-dibenzylidenacetone (2a) yielded besides the expected products also the branched acetal esters 13a and 13b.Formation of the anomalous products 7 and 13 can be rationalized assuming a common cyclopropanone type intermediate.
- Antus, Sandor,Boross, Ferenc,Kajtar-Peredy, Maria,Radics, Lajos,Nogradi, Mihaly
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p. 1283 - 1295
(2007/10/02)
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