57533-34-3Relevant academic research and scientific papers
Nitrogen Bridgehead Compounds. Part 42. Cyclization of Diethyl 2-(2-Pyridylaminomethylene)-succinates and -glutarates in Ethanolic Sodium Ethoxide
Vasvari-Debreczy, Lelle,Hermecz, Istvan,Meszaros, Zoltan
, p. 1799 - 1804 (2007/10/02)
2-(Pyridylaminomethylene)-succinates (1) and -glutarates (2) were treated with ethanolic sodium ethoxide solution.The succinates (1) gave, in reversible reactions, pyridopyrimidines (3) and pyridylpyrrolinones (5), and also underwent Z-E geometric isomerization.The cyclizations (Z)-(1) to (3) and (E)-(1) to (5) were more rapid than the isomerization of (1).Thus, short (1-min) reactions starting from (Z)-(1) produced the pyridopyrimidine (3) and those from (E)-(1) the pyridylpyrrolinone (5) in good yield.Longer (15-min) reactions yielded equilibrium mixtures, consisting mainly of pyridylpyrrolinones (5).Substituents at position 6 of the pyridine ring inhibited the formation of the pyridopyrimidines, whereas those at position 3 hindered or inhibited the formation of the pyridylpyrrolinones.The unsubstituted glutarate (2a) formed the pyridopyrimidine (4a) whereas the 6-substituted ones did not yield any cyclic product.Results of the sodium ethoxide ring closure were compared with those of the previously studied POCl3 - PPA and thermal cyclizations.
Nitrogen Bridgehead Compounds. Part 6. Ring Transformation. Part 3. Thermal Cyclization of Diethyl 2-(2-Pyridylaminomethylene)-succinates and -glutarates
Vasvari-Debreczy, Lelle,Hermecz, Istvan,Meszaros, Zoltan,Dvortsak, Peter,Toth, Gabor
, p. 227 - 232 (2007/10/02)
The pyridylsuccinates (1) and pyridylglutarates (2), with various substituents on the pyridine ring, were cyclized in Dowtherm A at 250 deg C.The succinates cyclized in two competing reaction routes, giving rise to pyridopyrimidines (route A) and N-pyridylpyrrolinones (route B).The ratio of the two products varied with the nature of the substituent and its position.The N-pyridylpyrrolinones proved to be mixtures of the desmotropes (5) and (6) which were separated.The pyridylglutarates (2) gave only the pyridopyrimidines (4).The 6-substituted pyridopyrimidines underwent a ring-transformation reaction at or above 250 deg C, forming the corresponding 1,8-naphthyridines (8) and (9).
