Metalation of Benzotrifluoride

Roberts, John D.; Curtin, David Y.

doi:10.1021/ja01212a090

Cited by 111 publications

(71 citation statements)

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“…[2] A repetition of this work with modern analytical equipment confirmed the data. [3] By the use of N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDTA)-activated sec-butyllithium (in tetrahydrofuran at À 75 8C) as a more energetic base (LIS-PMDTA), we were able to improve the yields, but could not secure product homogeneity (47 % 1 a contaminated with 25 % 1 b and 6 % 1 c).…”

Section: Resultssupporting

confidence: 70%

Bis- and Oligo(trifluoromethyl)benzenes: Hydrogen/Metal Exchange Rates and Gas-Phase Acidities

et al. 1998

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Abstract:The proton mobilities (kinetic acidities) of bis-and tris(trifluoromethyl)benzene are dictated to a large extent by steric factors; the trifluoromethyl group is a fairly bulky substituent that can seriously impede the approach of the metalating reagent. Most satisfactory results in terms of yields and selectivities have been achieved with lithium 2,2,6,6-tetramethylpiperidide or with methyllithium in the presence of potassium tert-butoxide, a slim version of the standard superbase. The rates of deprotonation under irreversible conditions do not parallel the thermodynamic (equilibrium) acidities. Substituent effects on the deprotonation energies in the gas phase appear to be additive: each trifluoromethyl group lowers it by 13 kcal mol À1 when located ortho with respect to the carbanion, and by 10 kcal mol À1 when located in a meta or para position.

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Section: Resultssupporting

confidence: 70%

Bis- and Oligo(trifluoromethyl)benzenes: Hydrogen/Metal Exchange Rates and Gas-Phase Acidities

et al. 1998

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“…When butyllithium in refluxing diethyl ether is employed as the reagent, subsequent trapping of the organometallic intermediates with carbon dioxide affords, besides o-(trifluoromethyl)benzoic acid (24 %), substantial amounts of the meta isomer (9 %) and traces of the para isomer (0.2 %) (Scheme 2). [74] Only the superbasic mixture of butyllithium and potassium tert-butoxide in tetrahydrofuran at À 75 8C is capable of accomplishing clean ortho metalation (67 %). [70,75] Scheme 2.…”

Section: Mono- Bis- and Tris(trifluoromethyl)benzenesmentioning

confidence: 99%

Parametrization of Substituents: Effects of Fluorine and Other Heteroatoms on OH, NH, and CH Acidities

Schlosser¹

1998

Angewandte Chemie International Edition

284

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Fluorine, the heterosubstituent par excellence, which can have a stronger impact on the reactivity in its vicinity than any other element, may serve as a crucial test of any model of the origin and transmission of electronic effects. To what extent fluoro substituents in organic compounds (A-H) increase their kinetic proton mobility (H/D and H/metal (M) exchange) and thermodynamic acidity in aqueous media and in the gas phase (see below) depends on many factors such as induction, resonance, polarization, hyperconjugation, and dipolar interactions.

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“…[3,4] In organolithium chemistry, the pioneering work of Gilman, Wittig, Roberts, and Curtin on ortho lithiations was seminal. [5][6][7] Suggested roles for reactive complexes in exchanges of hydrogen for lithium have been recurrent in the last 50 years. [8,9] Yet, two contemporary questions remain: 1) Does convincing evidence exist for the formation of complexes on the reaction pathway?…”

Section: Introductionmentioning

confidence: 99%

Beyond Thermodynamic Acidity: A Perspective on the Complex‐Induced Proximity Effect (CIPE) in Deprotonation Reactions

et al. 2004

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The concept of the complex-induced proximity effect (CIPE) in deprotonations is helpful in elucidating the mechanisms involved in carbanion chemistry and in planning organic syntheses. In this Review, the consequences of complexation of organolithium bases to functional groups of the substrates before the proton-transfer step are discussed. Experimental data from kinetic measurements and isotope-labeling experiments as well as the results of calculations in many cases point to a prelithiation complex as a reaction intermediate. Some examples from natural products synthesis illustrate how this concept can be used to obtain intermediates in a regio- or stereoselective manner. Of particular interest is the functionalization of positions that are remote from the coordination group.

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Metalation of Benzotrifluoride

Cited by 111 publications

References 0 publications

Bis- and Oligo(trifluoromethyl)benzenes: Hydrogen/Metal Exchange Rates and Gas-Phase Acidities

Bis- and Oligo(trifluoromethyl)benzenes: Hydrogen/Metal Exchange Rates and Gas-Phase Acidities

Parametrization of Substituents: Effects of Fluorine and Other Heteroatoms on OH, NH, and CH Acidities

Beyond Thermodynamic Acidity: A Perspective on the Complex‐Induced Proximity Effect (CIPE) in Deprotonation Reactions

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