The intermolecular reaction of phenols with propiolicesters in TFA in the presence of a Pd(OAc)2 catalyst, affording coumarin derivatives, is described. An exclusive formation of 5,6,7-trimethoxy-...
Metal Triflate-Catalyzed Regio- and Stereoselective Friedel–Crafts Alkenylation of Arenes with Alkynes in an Ionic Liquid: Scope and Mechanism
作者:Mi Young Yoon、Jin Hong Kim、Doo Seoung Choi、Ueon Sang Shin、Jin Yong Lee、Choong Eui Song
DOI:10.1002/adsc.200700039
日期:2007.7.2
In the metaltriflate-catalyzed hydroarylation of alkynes, employing an ionicliquid dramatically enhanced the catalytic activities, resulting in broadening the scope of substrates (arenes and alkynes). In some cases, even reactions that were not possible in conventional organic solvents proceeded smoothly in ionicliquids. Moreover, the ionicliquid phase containing catalyst could be readily recovered
在金属三氟甲磺酸酯催化的炔烃加氢芳基化中,采用离子液体显着增强了催化活性,从而扩大了底物(芳烃和炔烃)的范围。在某些情况下,甚至在常规有机溶剂中不可能发生的反应在离子液体中也能顺利进行。而且,通过在反应后简单地倾析有机层,可以容易地回收含离子液体的催化剂,并且可以将其重新用于随后的运行中而没有任何明显的活性损失。包括反应中间体的13 C NMR分析和同位素实验在内的机理研究首次证实,这种类型的反应是通过乙烯基阳离子中间体进行的。
Cyclization of aryl 3-aryl propynoates into 4-arylcoumarins catalyzed by cyclometalated Platinum(II) complexes
作者:Olesia Zaitceva、Valérie Bénéteau、Dmitry S. Ryabukhin、Ivan I. Eliseev、Mikhal A. Kinzhalov、Benoit Louis、Aleksander V. Vasilyev、Patrick Pale
DOI:10.1016/j.tet.2020.131029
日期:2020.4
Cyclometalated (ppy)PtII complexes (ppy = 2-phenylpyridinato-C2,N) catalyze the intramolecular cyclization of aryl propynoates to form coumarins and benzocoumarins. The complex [(ppy)PtCl(MeCN)] (5 mol %) was the most active and efficient catalyst for such reaction, especially in the presence of AgSbF6 (15 mol %) in 1,2-dichloroethane. With this catalytic system, a wide range of substituents and functional
Synthesis of coumarins by Pt-catalyzed hydroarylation of propiolic acids with phenols
作者:Juzo Oyamada、Tsugio Kitamura
DOI:10.1016/j.tet.2006.04.080
日期:2006.7
Synthesis of coumarins from phenols and propiolicacids was examined by using a Pt catalyst such as PtCl2/AgOTf, K2PtCl4/AgOTf, and K2PtCl4/AgOAc. Propiolicacid reacted even with less reactive phenols in trifluoroacetic acid to give coumarins and dihydrocoumarins. In the case of substitutedpropiolicacids, phenylpropiolic acid and 2-octynoic acid, the reactions proceeded selectively to afford coumarins
A direct route to coumarin derivatives from phenols and propiolic acids has been developed. Phenols react with propiolic acids in the presence of Pd(OAc) 2 as a catalyst to give coumarins in good yields. The simple process occurs under mild conditions without any additives.