不同取代基的苯甲醛制备相应取代基的乙炔苯

Preparation of Different Substituent Ethynylbenzene from its Corresponding Benzaldehyde

通过4步反应获得了12种不同取代基的乙炔基苯,并以良好或优异的产率得到了末端炔烃。即通过不同取代基苯甲醛与丙二酸发生Knoevenagel反应得到了不同取代基的3-苯基丙烯酸;在冰醋酸存在下,将不同取代基的3-苯基丙烯酸分别与液体溴反应,得到相应取代基的2,3-二溴-3-苯基丙酸;含不同取代基的2-溴乙烯基苯是由相应取代基的2,3-二溴-3-苯基丙酸在Et_(3)N/DMF中的反应合成;通过不同取代基的2-溴乙烯基苯与氢氧化钾的反应得到所需的不同取代基乙炔基苯。当取代基为溴时,产物具有最佳产率,而当取代基为硝基和叔丁基时,产率低。这表明不同的电子效应对产物的产率有很大的影响。

12 Different substituents of ethynylbenzene were obtained, and terminal alkynes were obtained with good or excellent yield through the following four steps.Different substituents of 3-phenylacrylic acid were given by reaction of different substituents of benzaldehyde with malonic acid by Knoevenagel condensation.Reaction of different substituents of 3-phenylacrylic acid with liquid bromine in the presence of glacial acetic acid afforded 2,3-dibromo-3-phenyl propanoic acid with corresponding substituents.2-Bromovinylbenzene with different substituents was synthesized from the reaction of 2,3-dibromo-3-phenylpropionic acid with corresponding substituents in Et_(3)N/DMF system.Ethynylbenzene with different substituents of the desired product was obtained by reaction of 2-bromovinylbenzene with different substituents with potassium hydroxide.When the substituent is bromine, the product has the best yield, and when the substituent was nitro and tert-butyl, the yield is low.It indicates that different electronic effects have a great effect on the yield of the products.