A new synthesis of 6-aminonicotinic acid derivatives was developed starting from the readily available 3-substituted acrylamidines 1 and electron-poor alkynes 2. By nucleophilic addition of the basic amidinic NH to the electron-poor triple bond, the intermediate azatrienes 4 were obtained. Through thermally induced electrocyclization compounds 4 afforded the pyridines 3 by alcohol elimination or oxidation. Another approach was the direct cyclization of acrylamidines with the dienyne system as a backbone. (C) 2000 Elsevier Science Ltd.
Isothiazoles. Part 11: 3-Azahexatrienes from 2-arylpropenamidines: Electrocyclization to 6-aminonicotinic acid derivatives / E.M. Beccalli, F. Clerici, M.L. Gelmi. - In: TETRAHEDRON. - ISSN 0040-4020. - 56:27(2000), pp. 4817-4821.
Isothiazoles. Part 11: 3-Azahexatrienes from 2-arylpropenamidines: Electrocyclization to 6-aminonicotinic acid derivatives
E.M. BeccalliPrimo
;F. ClericiSecondo
;M.L. GelmiUltimo
2000
Abstract
A new synthesis of 6-aminonicotinic acid derivatives was developed starting from the readily available 3-substituted acrylamidines 1 and electron-poor alkynes 2. By nucleophilic addition of the basic amidinic NH to the electron-poor triple bond, the intermediate azatrienes 4 were obtained. Through thermally induced electrocyclization compounds 4 afforded the pyridines 3 by alcohol elimination or oxidation. Another approach was the direct cyclization of acrylamidines with the dienyne system as a backbone. (C) 2000 Elsevier Science Ltd.Pubblicazioni consigliate
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