Cerium-Catalyzed Formal Cycloaddition of Cycloalkanols with Alkenes through Dual Photoexcitation
摘要:
We describe a synergistic utilization of cerium photocatalysis and photoinduced electron transfer catalysis that enables an atom- and step-economical ring expansion of readily available cycloalkanols. This operationally simple protocol provides rapid access to privileged and synthetically challenging bridged lactones. The mild catalytic manifold has been adapted to continuous flow for scale-up applications and employed for the concise synthesis of polycyclic core of nepalactones.
cyclopentane/[PdCl(C3H5)]2 efficiently catalyses the Heck reaction of disubstituted alkenes such as methyl crotonate, ethyl cinnamate, methyl methacrylate or α-methylstyrene with a variety of aryl halides. In the presence of 1,2-disubstituted alkenes the stereoselectivities of the reactions strongly depend on the substituents of the alkenes. Selectivities up to 97% in favor of E-isomers can be obtained
顺式,顺式,顺式-1,2,3,4-四(二苯基膦甲基)环戊烷/ [PdCl(C 3 H 5)] 2有效催化巴豆酸甲酯,肉桂酸乙酯,甲基丙烯酸甲酯或α等二取代烯烃的Heck反应-甲基苯乙烯与各种芳基卤化物。在1,2-二取代的烯烃的存在下,反应的立体选择性强烈取决于烯烃的取代基。添加到巴豆酸甲酯中可以得到高达97%的选择性,有利于E-异构体。用1,1-二取代的烯烃获得甲基丙烯酸甲酯或α-甲基苯乙烯的产物混合物。
Catalytic cross-coupling of diazo compounds with coinage metal-based catalysts: an experimental and theoretical study
作者:Ivan Rivilla、W. M. C. Sameera、Eleuterio Alvarez、M. Mar Díaz-Requejo、Feliu Maseras、Pedro J. Pérez
DOI:10.1039/c2dt32439c
日期:——
We examined the ability of TpxM (Tpx = hydrotris(pyrazolyl)borateligand; M = Cu and Ag) and IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene; M = Cu, Ag, Au) complexes as catalyst precursors for the cross-coupling of diazo compounds. Experimental data showed that the metal centre can be tuned with the appropriate selection of the ligand to yield either the homo- or hetero-coupling (cross-coupling)
我们检查了Tp x M(Tp x =氢三(吡唑基)硼酸酯配体; M =铜和银)和IPrMCl(IPr = 1,3-双(二异丙基苯基)咪唑-2-亚基; M = Cu,Ag, Au)络合物作为重氮化合物交叉偶联的催化剂前体。实验数据表明,该金属中心可以与配体的适当的选择,以产生任一同源或异源偶联(交叉耦合)的产品来调整。通过对反应机理的计算研究,合理化了实验反应模式,并确定了控制选择性的关键反应步骤:金属碳烯中间体与一种重氮化合物之间的初始反应。
Synthesis of α,β-Alkynyl Esters and Unsymmetrical Maleate Esters Catalyzed by Pd/C; An Efficient Phosphine-Free Catalytic System for Oxidative Alkoxycarbonylation of Terminal Alkynes
作者:Bhalchandra Bhanage、Sandip Gadge
DOI:10.1055/s-0032-1316896
日期:——
Pd/C-catalyzed oxidative alkoxycarbonylation of terminal alkynes using alcohols in the presence of tetrabutylammonium iodide under CO/O-2 (5:1 atm) has been investigated. The desired alpha,beta-alkynyl esters and unsymmetrical maleate esters are formed in good to excellent yields under different reaction conditions. The present protocol eliminates the use of phosphine ligands and has straightforward catalyst recovery. The catalyst was recycled up to six times without significant loss of catalytic activity.
A Novel Stereoselective Synthesis of Maleate Derivatives via Palladium-Catalyzed Dicarboalkoxylation of Terminal Alkynes
作者:Jinheng Li、Huanfeng Jiang、Lanqi Jia
DOI:10.1080/00397919908086012
日期:1999.11
Alkynes were dicarboalkoxylated efficiently and stereoselectively in high yields reacting for about 2h under atmospheric pressure of carbon monoxide at room temperature using a catalytic amount of PdCl2 and a stoichiometric amount of CuCl2.
High-Speed, Highly Fluorous Organic Reactions
作者:Kristofer Olofsson、Sun-Young Kim、Mats Larhed、Dennis P. Curran、Anders Hallberg