Organozinc mediated reactions

Knöchel, Paul; Perea, Juan J. Almena; Jones, Philip S.

doi:10.1016/s0040-4020(98)00318-4

Cited by 322 publications

(137 citation statements)

References 304 publications

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“…A reduction of the reaction time to 2 h and an increase in the amount of maleic anhydride to 10 equivalents, however, afforded isomerically pure 4-substituted piperidines in excellent overall yields (Scheme 1). For the fluorine-containing derivative, 19 F NMR spectroscopy was used to monitor the disappearance of the 2-isomer. Scheme 1.…”

Section: Resultsmentioning

confidence: 99%

Efficient Solution‐Phase Parallel Synthesis of 4‐Substituted N‐Protected Piperidines

Wang

Kauppi

Olsson³

et al. 2003

Eur J Org Chem

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Practical conditions for the synthesis of 4‐substituted N‐protected piperidines through CuCN·2LiBr‐catalyzed organozinc additions to 1‐acylpyridinium salts and subsequent hydrogen‐transfer hydrogenation have been established. The reaction sequence is performed at room temperature and provides 4‐substituted N‐protected piperidines in excellent overall yields without the isolation of intermediate dihydropyridines. In those cases in which the organozinc addition results in mixtures of 2‐ and 4‐substituted dihydropyridines, the 2‐substituted isomers are efficiently scavenged with maleic anhydride and subsequently removed by a mild extractive workup with NaHCO3 (sat.). The N‐acyl group can conveniently be exchanged from N‐phenoxycarbonyl to N‐tBoc, thus allowing orthogonal deprotection strategies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Resultsmentioning

confidence: 99%

Efficient Solution‐Phase Parallel Synthesis of 4‐Substituted N‐Protected Piperidines

Wang

Kauppi

Olsson³

et al. 2003

Eur J Org Chem

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“…32,33,52 These reagents have a similar reactivity to RLi or RMgBr reagent derived cyanocuprates, and a Cu-CN bond is formed at some point during transmetallation. 32,52,53 For the substitution reactions of cuprates, an oxidative addition-reductive elimination mechanism proceeding via a copper(III) intermediate rather than a direct displacement is proposed. 52,54,55 A conceptual framework for the mechanism is given in Scheme 7, involving catalytic formation of copper(I) intermediate RCu(CN)ZnCl (14a-g), nucleophilic oxidative addition of 14a-g to 5f to give a dimethylmethaneimino-containing copper(III) intermediate 15a-g, followed by reductive elimination of 15a-g to the product and catalyst.…”

Section: Methodsmentioning

confidence: 99%

Competitive kinetic study of the amination of organomagnesium and -zinc reagents with acetoneO-sulfonyloxime

Erdık

Ömür

2005

Appl. Organometal. Chem.

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Kinetic studies are reported for the electrophilic amination of substituted phenylmagnesium bromides and CuCN-catalyzed phenylzinc chlorides with acetone O-(2,4,6-trimethylphenylsulfonyl)oxime in tetrahydrofuran at reflux temperature and at room temperature respectively. Substituent effects were determined by competition experiments. Rate data are analyzed via Hammett relationships to support the proposed mechanisms for the substitution of these organometallics with an electrophilic amino transfer reagent.

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“…Even though the asymmetric inductions obtained with [Ir((S)-PHOX)] might be considered good enough for an application in the industrial synthesis of fragrant materials, we decided to further investigate the asymmetric hydrogenation of the acrylic acid 17, being also spurred on by the observation that there are only a few studies dealing with the hydrogenation of acrylic acids bearing only a substituent in a-position, such as realized in 17 [32] [33]. Thus, we tested the hydrogenation of 17 with the [Ru(C 6 H 6 )Cl 2 ] 2 /(S)-BINAP system (1 : 2 molar ratio complex/ligand); the relevant data are reported in the Table. A preliminary experiment carried out at 08 under 100 atm of H 2 furnished quite disappointing results (Entry 1): the catalyst appeared scarcely active and able to grant only a moderate asymmetric induction, providing (S)-18 with 35% ee.…”

Section: Citralismentioning

confidence: 99%

Homogeneous Asymmetric Catalysis in Fragrance Chemistry

Ciappa

Bovo

Bertoldini

et al. 2008

Chemistry & Biodiversity

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Opposite enantiomers of a chiral fragrance may exhibit different olfactory activities making a synthesis in high enantiomeric purity commercially and scientifically interesting. Accordingly, the asymmetric synthesis of four chiral odorants, Fixolide, Phenoxanol, Citralis, and Citralis Nitrile, has been investigated with the aim to develop practically feasible processes. In the devised synthetic schemes, the key step that leads to the formation of the stereogenic center is the homogeneous asymmetric hydrogenation of a prochiral olefin. By an appropriate choice of the catalyst and the reaction conditions, Phenoxanol, Citralis, and Citralis Nitrile were obtained in high enantiomeric purity, and odor profiles of the single enantiomers were determined.

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Organozinc mediated reactions

Cited by 322 publications

References 304 publications

Efficient Solution‐Phase Parallel Synthesis of 4‐Substituted N‐Protected Piperidines

Efficient Solution‐Phase Parallel Synthesis of 4‐Substituted N‐Protected Piperidines

Competitive kinetic study of the amination of organomagnesium and -zinc reagents with acetoneO-sulfonyloxime

Homogeneous Asymmetric Catalysis in Fragrance Chemistry

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