Palladium-catalyzed homocoupling reactions of organic tellurides
摘要:
Organic tellurides containing a styryl moiety react in acetonitrile to give the corresponding homocoupling products, 1,3-dienes, with moderate to quantitative yields in the presence of a catalytic amount of Pd(OAc)(2) together with AgOAc at 25 degrees C. In contrast, such homocoupling reactions hardly occur with diaryl, alkyl aryl, dialkyl, and alkynyl aryl tellurides, even at reflux temperature and in the presence of a stoichiometric amount of palladium salt, in disagreement with reported results. The result of cross-over experiments suggests that this homocoupling reaction occurs between an alkenyl telluride and an alkenylpalladium species, the latter being formed via the migration of an alkenyl moiety from Te to Pd (transmetallation).
Glycerol/CuI/Zn as a recyclable catalytic system for synthesis of vinyl sulfides and tellurides
作者:Lóren C.C. Gonçalves、David B. Lima、Pedro M.Y. Borba、Gelson Perin、Diego Alves、Raquel G. Jacob、Eder J. Lenardão
DOI:10.1016/j.tetlet.2013.04.119
日期:2013.6
Cu-catalyzed coupling of diphenyl disulfide and diphenyl ditelluride with vinyl bromides using a recyclable catalytic system and glycerol as a green solvent is described. This protocol was efficiently used in the preparation of vinylsulfides and vinyl tellurides with a variety of substituents in good yields and stereoselectively. The solvent/catalyst system was directly reused for four cycles without loss
A simple and general preparation of vinylic sulfides, selenides and tellurides
作者:Claudio C. Silveira、Paulo Cesar S. Santos、Samuel R. Mendes、Antonio L. Braga
DOI:10.1016/j.jorganchem.2008.09.039
日期:2008.12
A general method for the synthesis of vinylic chalcogenides by nucleophilic and Ni-catalyzed vinylic substitution on vinylichalides by phenyl chalcogenolates is described. The reactions were regio and stereoselective for the nickel catalyzed substitution, and mixture of isomers was observed for some examples in the thermal process in DMF.
Influence of the gegenion in the transmetalation reaction of vinylic tellurides with higher order cyanocuprates
作者:André Chieffi、João V. Comasseto
DOI:10.1016/s0040-4039(00)73112-1
日期:1994.6
Dilithium cyanocuprates R2LCu(CN)Li2 (L=2-Th, Me) react with vinylictellurides of Z configuration, RCHCHTeR1 to give higherordervinyliccyanocuprates, [(RCHCH)LCu(CN)Li2]. By changing the gegenion from lithium to magnesium [R2LCu(CN)LiMgBr or R2LCu(CN)(MgBr)2] the reaction gives cross - coupling products of Z configuration, RCHCHR2 in good yields.
Vinylic chalcogenides were synthesized stereospecifically by hydrochalcogenation of propargylic amines or alcohols mediated by cerium(III) chloride. The products were obtained in good yields and with high regio- and stereoselectivities. cerium chloride - vinylic chalcogenides - hydrochalcogenation - selenium - tellurium
Phosphine-nickel(II), -cobalt(II), -palladium(0) and -palladium(II) complexes as catalysts in cross-coupling reactions of aryl- and alkyl-grignard reagents with organic tellurides
作者:Sakae Uemura、Shin-Ichi Fukuzawa、Suresh R. Patil
DOI:10.1016/0022-328x(83)80215-0
日期:1983.2
in good to moderate yields, with elemental tellurium being formed as a black precipitate. A catalytic reduction-oxidation cycle involving a Ni or Co complex bearing an organotellurium moiety (RTe; R alkenyl, aryl, and alkyl) is proposed for the reaction. Palladium catalysts such as Pd(PPh3)4, PdCl2(PPh3)2, and PdCl2(PhCN)2 are revaled to be much less effective than the Ni and Co catalysts in both the