- Nickel-catalyzed conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds with the aid of a catalytic amount of an alkyne
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Alkynes in combination with a catalytic amount of a nickel complex were found to catalyze the conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds, where use of an optically active alkyne induces the asymmetric addition. Copyright
- Shirakawa, Eiji,Yasuhara, Yuichi,Hayashi, Tamio
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- Indium-catalyzed coupling reaction between silyl enolates and alkyl chlorides or alkyl ethers
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The coupling reactions of alkyl chlorides with silyl enolates catalyzed by InBr3, and the coupling reactions of alkyl ethers with silyl enolates catalyzed by the combined Lewis acid of InBr3/Me3SiBr are described. In both reaction systems, various types of silyl enolates were used to give corresponding α-alkylated esters, ketones, carboxylic acids, amides, thioesters, and aldehydes.
- Nishimoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
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experimental part
p. 5462 - 5471
(2009/12/01)
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- Mechanism of the Grignard Adddition Reaction. XVI. Homolytic and Concerted Mechanisms in the Reaction of α,β-Unsatureted Carbonyl Compounds with Grignard Reagents
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Kinetic measurements have shown that the addition of Grignard reagents to α,β-unsaturated carbonyl compounds takes place either by a concerted mechanism or by a homolytic mechanism.Phenylmagnesium bromide, which is incapable of homolysis, reacts rapidly in a 1,4-fashion if an s-cis conformation exists between the C=C and the C=O bonds, but only 1,2-addition takes place if the conformation is s-trans.tert-Butylmagnesium bromide is unsuited to the concerted reaction, but 1,4-addition takes place via homolysis.Primary and secondary Grignard reagents, like phenyl, react rapidly in a concerted manner with s-cis substrates, but unlike phenyl, these Grignard reagents may, with s-trans substrates, produce some 1,4-adduct via the homolytic mechanism.
- Holm, Torkil
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p. 925 - 929
(2007/10/02)
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- Synthese de tertiobutylcetones α-azotees de type =N-C(R1)(R2)-CO-C(CH3)3
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The α-nitrogen-ketones 2, 3 and 4 were prepared from α-bromoketones.These were synthesized by the bromination of the ketones which had been obtained by the pinacolone or benzyltertiobutylketone alkylation from the corresponding halo-derivatives.We have observed that the bromination of the ketones depends to some extent upon the nature of these compounds.
- Montignoul, Claude,Richard, Marie-Josee,Vigne, Christian,Giral, Louis
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p. 1509 - 1519
(2007/10/02)
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