345894-07-7Relevant academic research and scientific papers
Acid-catalyzed conversions of N-(4-nitrobenzylidene)-2-cyclopropyl And N-(4-nitrobenzylidene)-2-alkenylanilines. A new method for the synthesis of dihydroquinolines and quinolines
Trofimova,Fedotov,Mochalov,Shabarov,Zefirov
, p. 1198 - 1205 (2007/10/03)
The acid-catalyzed conversions of N-(4-nitrobenzylidene)-2-cyclopropyl- and N-(4-nitrobenzylidene)-2-alkenylanilines have been studied. It has been established that the protonated azomethine unit of N-(4-nitrobenzylidene)-2-cyclopropylanilines is not capable of initiating intramolecular heterocyclization with participation of the three-membered ring. Conversion of N-(4-nitrobenzylidene)-2-(1-methylcyclopropyl)aniline to derivatives of quinoline is possible under the influence of concentrated H2SO4. Under the same conditions 2-methylcyclopropyl- and cyclopropyl-substituted Schiff's bases form only the corresponding alkenylazomethines (isomerization of the three-membered ring). Under the influence of more moderate acids (trifluoroacetic, polyphosphoric) N-(4-nitrobenzylidene)-2-propenyl- and N-(4-nitrobenzylidene)-2-buten-2-yl)anilines are converted to the corresponding dihydroquinolines and quinolines in high yields. N-(4-Nitrobenzylidene)-2-(2,2- dimethylvinyl)aniline does not form derivatives of quinoline under the influence of the same acids in the given conditions.
