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。
Pd-Catalyzed Threefold Arylation of Baylis-Hillman Bromides and Acetates with Triarylbismuth Reagents
作者:Maddali L. N. Rao、Somnath Giri
DOI:10.1002/ejoc.201200543
日期:2012.8
alkyl 2-benzylacrylates and 2-benzylacrylonitriles were synthesized by means of atom-economic cross-couplings of Baylis–Hillmanbromides or acetates with BiAr3 under palladium-catalyzed conditions. These reactions, involving threefold aryl couplings using BiAr3 reagents with bromides and acetates, are fast and are completed in 1–2 h with high product yields.
The metal- and photocatalyst-free synthesis of substituted allylarenes has been carried out under visiblelightdriven conditions. The process was based on the photogeneration of aryl radicals from arylazosulfones and their ensuing reaction with allyl sulfones. The developed procedure was very efficient when using substrates bearing electron-withdrawing groups, and allowed for the preparation of α-benzyl
α‐Thianthrenium Carbonyl Species: The Equivalent of an α‐Carbonyl Carbocation
作者:Hao Jia、Tobias Ritter
DOI:10.1002/anie.202208978
日期:2022.9.26
We report α-thianthrenium carbonyl species as α-carbonyl carbocation equivalents, generated in situ by radical conjugate addition of trifluoromethyl radical to Michael acceptors. The method can obtain Cα-tetrasubstituted amino acids in 90 seconds.
Stereoselective homogeneous catalytic arylation of methyl methacrylate: Experimental and computational study
作者:Zorica D. Petrović、Vladimir P. Petrović、Dušica Simijonović、Svetlana Marković
DOI:10.1016/j.molcata.2012.01.007
日期:2012.4
Catalytic systems trans-[PdCl2(DEA)(2)]/DEA and trans-[PdCl2(DEA)(2)]/[DEA][HAc], used in the model reaction of methyl methacrylate with iodobenzene, 4-iodoanisole, and bromobenzene, provide homogeneous catalysis, good regioselectivity and excellent stereoselectivity. The major product of the regioselective reaction is internal olefin. In all examined cases the only stereoisomer of the internal olefin methyl 3-phenyl-2-methylpropenoate is the E-isomer, whereas the only stereoisomer of the double arylated reaction product methyl 2-benzyl-3-phenylpropenoate is the Z-isomer. A DFT study, which investigates mechanistic aspects of migratory insertion, beta-hydride elimination and reductive elimination of this phosphine-free Heck reaction, is in agreement with our experimental findings. (C) 2012 Elsevier B.V. All rights reserved.