Dipole-stabilized carbanions:  novel and useful intermediates

Beak, Peter; Reitz, David B.

doi:10.1021/cr60313a004

Cited by 218 publications

(77 citation statements)

References 35 publications

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“…The results are compiled in Table 1. As expected, diisopropyl methyl phosphate (6a) was deprotonated regioselectively at the methyl group giving the dipole-stabilized [12] α-oxymethyllithium compound 7a. This species is very likely to be short-lived, because the phosphoryl group migrates intramolecularly (1,2-migration of phosphorus, phosphateϪphosphonate rearrangement).…”

Section: Synthesis Of Phosphates and Regioselectivity Of Their Metallsupporting

confidence: 59%

“…[10] Recently, the range of phosphoryloxy-substituted organolithium compounds accessible by metallation of phosphates was extended significantly. [12] We found that triethyl, tri-n-propyl and tri-n-butyl phosphate can be deprotonated by sBuLi/TMEDA at Ϫ78°C. This finding caused us to study the regioselectivity and the primary kinetic isotope effect of the deprotonation of purely aliphatic phosphates, the configurational stability of the lithiated species, and the stereochemistry of the rearrangement at carbon.…”

Section: Introductionmentioning

confidence: 79%

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Metallation of Phosphorylated Aliphatic Alcohols to Configurationally Stable α-Oxyalkyllithium Compounds − Use of the Phosphoryl Group as an Activating Group and Electrophile

Hammerschmidt¹,

Schmidt²

2000

Eur. J. Org. Chem.

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Section: Synthesis Of Phosphates and Regioselectivity Of Their Metallsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 79%

Metallation of Phosphorylated Aliphatic Alcohols to Configurationally Stable α-Oxyalkyllithium Compounds − Use of the Phosphoryl Group as an Activating Group and Electrophile

Hammerschmidt¹,

Schmidt²

2000

Eur. J. Org. Chem.

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“…A topic that has been of fundamental interest in physical organic chemistry for half a century addresses the problem of bonding of a proton in a complex with benzene (22) and other aromatic nuclei and of its mobility within these resulting complexes (Scheme 7).…”

Section: In Memory Of Bob Squiresmentioning

confidence: 99%

Thermochemical Data of Organic Ions Obtained from Investigations in the More or Less “Diluted” Gas Phase

Kuck¹

2000

Angewandte Chemie International Edition

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How is a proton bound to an arene, how mobile is it in such a complex, and how much energy is required to remove it-these questions have been of fundamental interest in physical organic chemistry for half a century. The experimental determination of quantitative thermochemical data of organic elementary processes in the gas phase is discussed for recent examples, such as the alpha-acidification of tertiary amines by complexation with boranes (see reaction) and the "local" C(alpha)-H acidities of alpha,alpha,alpha-trifluoromethylbenzene and higher analogues.

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“…Electrostatic effects activate the C-2 position toward proton abstraction by strong bases while the N-oxide moiety induces decreased pair-pair electron repulsions and increased chelation in the formed lithiated species. Then, pyridine N-oxides ( Figure 15.2) are selectively metallated at the C-2 position by n-BuLi or LiTMP in moderate yields (24-34%) [35]. The addition of TMEDA or the presence of the -NHCOtBu group in C-2 position strongly increases the yield.…”

Section: Metallation Of Dipolar Adducts Of Pyridines (N-oxides or Bf mentioning

confidence: 99%

Lithiated Aza‐Heterocycles in Modern Synthesis

Fort

Comoy

2014

Lithium Compounds in Organic Synthesis

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Introduction Functional nitrogen-containing heteroaromatic compounds, especially sixmembered ones (pyridines, diazines, quinolines, and their fused derivatives), have attracted the attention of chemists worldwide because they play an important role in the development of new pharmaceuticals [1], agrochemicals [2], catalysts [3], or materials [4] (including polymers).Besides the classical reactions (i.e., electrophilic heteroaromatic substitutions on heterocycles or single electron-transfer (SET) mediated reactions with brominated derivatives) [5] and ex nihilo ring syntheses [6], metallation reactions providing organolithium compounds are of particular interest because they allow the direct functionalization starting from bare or sparsely substituted heterocycles intrinsically more acidic than similar benzene-ring systems. However, the strong bases used for metallation as well as the prepared organolithiums also exhibit a large propensity for nucleophilic addition. Further, though numerous methods have been described for the single derivatization, multiple functionalization often appears much more sensitive and difficult because of the complexation or aggregation phenomena observed either with primary substituents or with the nitrogen atom in the heterocycle itself. These complex phenomena, together with the variation in reaction conditions (temperature, solvent, ratio), produce various competitive reaction pathways. Thus, an arsenal of methodologies has then been developed to tune the regio-, chemio-, and sometimes stereoselectivities. The goal is generally to control these additional influences, providing variation of kinetic or thermodynamic acidity at various sites susceptible to lithiation.With a special focus on pyridines, quinolines, diazines, and fused pyridinic compounds, this chapter describes organolithium tools that allow (i) direct derivatization of bare N-containing heteroaromatics; (ii) metallation of dipolar adducts of pyridines and analogs; (iii) halogen/Li exchanges; (iv) ring metallation by using directing metallation groups; (v) lithiation invoking an halogen dance; and (vi) lateral and remote lithiations (Scheme 15.1). Next, the usefulness of these tools, often Lithium Compounds in Organic Synthesis: From Fundamentals to Applications, First Edition. Edited by Renzo Luisi and Vito Capriati.

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Dipole-stabilized carbanions: novel and useful intermediates

Cited by 218 publications

References 35 publications

Metallation of Phosphorylated Aliphatic Alcohols to Configurationally Stable α-Oxyalkyllithium Compounds − Use of the Phosphoryl Group as an Activating Group and Electrophile

Metallation of Phosphorylated Aliphatic Alcohols to Configurationally Stable α-Oxyalkyllithium Compounds − Use of the Phosphoryl Group as an Activating Group and Electrophile

Thermochemical Data of Organic Ions Obtained from Investigations in the More or Less “Diluted” Gas Phase

Lithiated Aza‐Heterocycles in Modern Synthesis

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