This is a new synthetic method for various 4-substituted-3-chromenes : phenyl propargyl ethers underwent intramolecular cyclization to give 4-chromene derivatives by heating with diethylaniline. The reaction mechanism was clarified by the study of substituted phenyl propargyl ethers under the consideration of their electronic effects on the yields of resulting 3-chromene ; in general, the presence of +R group enhanced the cyclization, whereas -R group gave much lower yields of the corresponding chromenes. Therefore, this intramolecular cyclization is concluded to be an electrophilic reaction.
这是一种合成多种4取代-3-
氟烯的新方法:苯
丙炔醚在与二乙ylaniline加热时经历了分子内环化反应,生成了4-
氟烯衍
生物。通过研究取代苯
丙炔醚及其对得到的3-
氟烯产率的电子效应,阐明了反应机理;一般来说,+R基团的存在增强了环化反应,而-R基团则导致相应的
氟烯产率显著降低。因此,可以得出结论,这种分子内环化反应是一种亲电反应。