Electroorganic reactions. Part 58. Revisiting the cleavage of oxalate ester radical-anions

Utley, James H. P.; Ramesh, Shalini

doi:10.3998/ark.5550190.0004.c03

Cited by 8 publications

(4 citation statements)

References 10 publications

(17 reference statements)

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“…The same approach has been successful in a study of the kinetics of cleavage of oxalate radical-anions. 11 For CV runs giving i pc /i pa between 0.2-0.4, allowing k 2 to float gave excellent fits between experimental and simulated CVs (see Fig. 3) except for the very slowest reactions.…”

Section: Kinetics Of Proton Transfermentioning

confidence: 68%

The reactivity, as electrogenerated bases, of chiral and achiral phenazine radical-anions, including application in asymmetric deprotonation

et al. 2005

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Radical-anions, electrochemically generated in aprotic solvent from C(2) symmetric homochiral phenazine derivatives, act as chiral electrogenerated bases (EGBs) in the desymmetrisation by selective deprotonation of a prochiral epoxide (3,4-epoxy-2,3,4,5-tetrahydrothiophene-1,1-dioxide); the anion produced is trapped by mesitoic anhydride. The phenazines may be recovered in high yield by air oxidation. Enantiomeric excesses are modest (8-34%) but this is to our knowledge the first demonstration of such stereoselective electrochemically-initiated deprotonation. The reactivity of phenazine radical-anions as EGBs has also been explored by measurements of the rates of proton transfer; the prochiral epoxide was found to have a kinetic acidity similar to that of the methyltriphenylphosphonium cation.

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Section: Kinetics Of Proton Transfermentioning

confidence: 68%

The reactivity, as electrogenerated bases, of chiral and achiral phenazine radical-anions, including application in asymmetric deprotonation

et al. 2005

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“…[113,114] Similar to the reactivity observed for p-toluate esters, the efficiency of the C(O)OÀ C bond cleavage in oxalate anion-radical intermediates was found highly dependent on the stability of the resulting C-radical. [115] Unlike the hydrobenzoin-derived monoethyl oxalate diesters (Figure 17, top left), electroreduction of monoethyl oxalate diesters of monoalcohols gave rise to less stabilized C-radicals, precluding fast homolytic CÀ O bond cleavage of the initially formed oxalate anion-radical. [116,117] As a result, the latter becomes amenable to hydrolysis by adventitious water or electrogenerated bases, leading to formation of an alcohol as sideproduct.…”

Section: Electrochemical Cà O Bond Activation In Carboxylic Estersmentioning

confidence: 99%

Electrosynthetic C−O Bond Activation in Alcohols and Alcohol Derivatives

et al. 2022

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Alcohols and their derivatives are ubiquitous and versatile motifs in organic synthesis. Deoxygenative transformations of these compounds are often challenging due to the thermodynamic penalty associated with the cleavage of the CÀ O bond. However, electrochemically driven redox events have been shown to facilitate the CÀ O bond cleavage in alcohols and their derivatives either through direct electron transfer or through the use of electron transfer mediators and electroactive catalysts. Herein, a comprehensive overview of preparative electrochemically mediated protocols for CÀ O bond activation and functionalization is detailed, including direct and indirect electrosynthetic methods, as well as photoelectrochemical strategies.

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“…Similar to the reactivity observed for p ‐toluate esters, the efficiency of the C(O)O−C bond cleavage in oxalate anion‐radical intermediates was found highly dependent on the stability of the resulting C‐radical. [115] Unlike the hydrobenzoin‐derived monoethyl oxalate diesters (Figure 17 , top left), electroreduction of monoethyl oxalate diesters of monoalcohols gave rise to less stabilized C‐radicals, precluding fast homolytic C−O bond cleavage of the initially formed oxalate anion‐radical. [ 116 , 117 ] As a result, the latter becomes amenable to hydrolysis by adventitious water or electrogenerated bases, leading to formation of an alcohol as side‐product.…”

Section: Electrochemical C−o Bond Activation In Carboxylic Estersmentioning

confidence: 99%