- A frustrated-Lewis-pair approach to catalytic reduction of alkynes to cis-alkenes
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Frustrated Lewis pairs are compounds containing both Lewis acidic and Lewis basic moieties, where the formation of an adduct is prevented by steric hindrance. They are therefore highly reactive, and have been shown to be capable of heterolysis of molecular hydrogen, a property that has led to their use in hydrogenation reactions of polarized multiple bonds. Here, we describe a general approach to the hydrogenation of alkynes to cis-alkenes under mild conditions using the unique ansa-aminohydroborane as a catalyst. Our approach combines several reactions as the elementary steps of the catalytic cycle: hydroboration (substrate binding), heterolytic hydrogen splitting (typical frustrated-Lewis-pair reactivity) and facile intramolecular protodeborylation (product release). The mechanism is verified by experimental and computational studies.
- Chernichenko, Konstantin,Madarasz, Adam,Papai, Imre,Nieger, Martin,Leskelae, Markku,Repo, Timo
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p. 718 - 723
(2013/08/23)
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- Catalytic homocoupling of aryl, alkenyl, and alkynyl halides with Ni(II)-complexes and zirconocene dichloride
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A new catalytic system (cat. (H)2Phen(Me)2· NiCl2 or (MeO)2Dipyr(H)2·NiCl 2, cat. Zr(cp)2Cl2, 2 equiv Mn, and 2 equiv LiCl) has been developed to facilitate the homocoupling of a wide range of aryl, alkenyl, and alkynyl halides.
- Peng, Jianbiao,Liu, Xiang,Kishi, Yoshito
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experimental part
p. 2172 - 2175
(2011/05/05)
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- Configurational Instability of α-Alkenyl and α-Alkynyl Vinyllithiums. Syntheses of Stereodefined 2-Alkyl-1-en-3-ynes
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Metal-halogen exchange of either (Z)-enynyl bromides or (Z)-dienyl bromides by sec-BuLi produces vinyllithiums that are configurationally stable only at temperatures below -120 deg C and -78 deg C, respectively.Allylation of (Z)-enynylalanates with allyl bromide or methylation of (Z)-enynyl bromides with CH3MgI and Fe(acac)3 catalyst furnishes the corresponding 2-alkyl-1-en-3-ynes.
- Miller, Joseph A.,Leong, William,Zweifel, George
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p. 1839 - 1840
(2007/10/02)
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- A Synthesis of Conjugated Dienes from Aromatic, Five-membered Heterocycles
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Reactions of furan, thiophene, selenophene, and tellurophene as well as 2-methyl and 2,5-dimethyl derivatives of the first two heterocycles with phenyl-, methyl-, and n-butyl-magnesium bromides in the presence of ligated nickel dichloride are shown to yield buta-1,3-dienes mostly with retention of configuration.
- Wenkert, Ernest,Leftin, Michael H.,Michelotti, Enrique L.
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p. 617 - 618
(2007/10/02)
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