Structure of lithium dimethylcuprate and mechanism of the Corey-Posner reaction

Pearson, Ralph G.; Gregory, Carl D.

doi:10.1021/ja00430a015

Cited by 143 publications

(46 citation statements)

References 11 publications

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“…Therefore, it seems reasonable to suggest that different substitution patterns in the aryl group of the organometallic reagent afford subtle changes in the structure of the cuprate and that these changes can affect the initial nucleo- phile-electrophile interaction and therefore affect the overall amenability towards side reactions. This suggestion is consistent with the generally accepted idea that the solution structure of cuprates (which may be dimeric 18 or an equilibrium mixture of several discrete identities 19 is highly dependent upon a number of factors, including solvent, temperature and counter-ion. 20 CONCLUSION This work has demonstrated that the reaction of lithium diarylcuprate(I) reagents with bromo-substituted aroyl chlorides is a highly convenient method for the preparation of synthetically useful bromobenzophenones.…”

Section: Resultssupporting

confidence: 90%

Preparation of o-bromobenzophenone derivatives from lithium diarylcuprate(I) reagents

Karagöz

Astley

2000

Appl. Organometal. Chem.

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The reaction of lithium diarylcuprate(I) reagents with o-bromobenzoyl chloride has been investigated. In general, the reaction proceeds well to give synthetically useful o-bromobenzophenone derivatives as the major product. It is suggested that a minor substituent effect, whereby diarylcuprate reagents containing an ortho or meta substituent react more favourably, may be attributed to small changes in the structure of the organometallic reagent.

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Section: Resultssupporting

confidence: 90%

Preparation of o-bromobenzophenone derivatives from lithium diarylcuprate(I) reagents

Karagöz

Astley

2000

Appl. Organometal. Chem.

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“…Its molecular weight indicates a (time-averaged) dimeric structure in diethyl ether and Me 2 S, and X-ray scattering studies support this conclusion by showing the CuÀCu distance in solution as 2.6 ± 2.8 , [125,130] which is close to the value in crystals. The extended X-ray absorption fine structure (EX-AFS) spectra in solution indicate dicoordination of the copper atom with a CÀCu bond length of 1.94 ± 1.96 .…”

Section: Dynamic Equilibria In Solutionmentioning

confidence: 56%

“…[124] The dimeric structure was further indicated in NMR spectroscopy, cryoscopic, and X-ray scattering experiments by Pearson and Gregory. [125] Following the first crystal structure determination of a R 2 CuLi by van Koten et al, [126] Weiss and Lorenzen, and Olmstead and Power determined various dimeric structures [{[Li(OEt 2 )]CuPh 2 } 2 ] (Figure 1 g), [127] [Li 2 (SMe 2 ) 3 -Cu 2 Ph 4 ], [118] and [{[Li(SMe 2 )]Cu(Me 3 SiCH 2 ) 2 } 2 ]. [128] These structures have their lithium cation tricoordinated (two R groups and one solvent molecule).…”

Section: Minimum Lithium Organocuprate Clusters: R 2 Culimentioning

confidence: 99%

Wherefore Art Thou Copper? Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry

Nakamura

Mori

2000

Angew. Chem. Int. Ed.

272

186

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Organocopper reagents provide the most general synthetic tools in organic chemistry for nucleophilic delivery of hard carbanions to electrophilic carbon centers. A number of structural and mechanistic studies have been reported and have led to a wide variety of mechanistic proposals, some of which might even be contradictory to others. With the recent advent of physical and theoretical methodologies, the accumulated knowledge on organocopper chemistry is being put together into a few major mechanistic principles. This review will summarize first the general structural features of organocopper compounds and the previous mechanistic arguments, and then describe the most recent mechanistic pictures obtained through high‐level quantum mechanical calculations for three typical organocuprate reactions, carbocupration, conjugate addition, and SN2 alkylation. The unified view on the nucleophilic reactivities of metal organocuprate clusters thus obtained has indicated that organocuprate chemistry represents an intricate example of molecular recognition and supramolecular chemistry, which chemists have long exploited without knowing it. Reasoning about the uniqueness of the copper atom among neighboring metal elements in the periodic table will be presented.

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“…[10] An early study by Pearson and Gregory concluded that halide-free Me 2 CuLi is dimeric in ether. [47] The structure of Me 2 CuLi´LiI in solution has not been established; the Pearson ± Gregory dimer A and the Bertz ± Snyder heterodimer B are predicted to have essentially the same NMR shifts. [48] In 1990, it was asserted that organocuprates are mainly monomers in THF, based on NMR studies.…”

Section: Reactions With Cyimentioning

confidence: 99%

Re-evaluation of Organocuprate Reactivity: Logarithmic Reactivity Profiles for Iodo- versus Cyano-Gilman Reagents in the Reactions of Organocuprates with 2-Cyclohexenone and Iodocyclohexane

Bertz¹,

Chopra

Eriksson

et al. 1999

Chem. Eur. J.

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Iodo-Gilman reagents Me 2 -CuLi´LiI, Bu 2 CuLi´LiI, and BuThCuLi´LiI and cyano-Gilman reagents (ne Â e ªhigher order cyanocupratesº Me 2 CuLi´LiCN, Bu 2 CuLi´LiCN, and BuThCuLi´LiCN react with 2-cyclohexenone at various rates, which depend upon the R groups (Me, Bu, Th thienyl), Li salt (LiI vs. LiCN), solvent (ether vs. THF), and amount of trimethylsilyl chloride (TMSCl) additive. The effect of the Li salt (CuI vs. CuCN precursor) is less than that of solvent or TMSCl. The butylcuprate-iodocyclohexane reaction has also been examined as a function of Li salt, solvent, and TMSCl additive, and similar effects are observed. The reactivity matrix R with elements r i,j is a convenient way to store and present a large amount of relative reactivity data. Entry r i,j is the ratio of the rate with reagent i to the rate with reagent j, which we approximate by using yields measured after a short time (4 s). The logarithmic reactivity profile (LRP) provides an efficient means for determining yields under conditions where such comparisons are valid. The results of a large number of 4-point LRPs and related reactions are tabulated and analyzed to provide a clearer picture of organocuprate reactivity.

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Structure of lithium dimethylcuprate and mechanism of the Corey-Posner reaction

Cited by 143 publications

References 11 publications

Preparation of o-bromobenzophenone derivatives from lithium diarylcuprate(I) reagents

Preparation of o-bromobenzophenone derivatives from lithium diarylcuprate(I) reagents

Wherefore Art Thou Copper? Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry

Re-evaluation of Organocuprate Reactivity: Logarithmic Reactivity Profiles for Iodo- versus Cyano-Gilman Reagents in the Reactions of Organocuprates with 2-Cyclohexenone and Iodocyclohexane

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