Studies on Electrolytic Substitution Reactions. I. Anodic Acetoxylation

Eberson, Lennart; Nyberg, Klas

doi:10.1021/ja00960a021

Cited by 124 publications

(42 citation statements)

References 3 publications

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“…More importantly, the signal direction indicates a positive hyperfine coupling constant for the cyclopropane protons. This assignment rules out any delocalization of spin onto the tertiary cyclopropane carbons as in structure type 13 and is compatible 'The oxidation potential of dimethoxybenzene is 1.34 V vs. SCE (21), that of fluorene is 1.65 V vs. SCE (22).…”

Section: Norcarene Clerivativessupporting

confidence: 53%

“…The first structure is essentially a styrene radical cation in which charge and spin are delocalized over eight carbon atoms and in which the cyclopropane ring is unaffected (21). In the second structure, the 3"-3" cyclopropane bond is broken and charge and spin are delocalized over ten carbon atoms (22). This structure implies a thorough reorganization of the three cyclopropane carbon atoms and its formation may require a substantial activation energy.…”

Section: Benzorzo~ca~adiet~ementioning

confidence: 99%

See 1 more Smart Citation

Radical cations of strained ring hydrocarbons. Cyclopropane derivatives

Roth¹,

Schilling²

1983

Can. J. Chem.

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Bell L[zbortrtorie.s, M~r r r r r~ H i l l . NJ 07974. U.S.A . Receivcd July 27, 1982This l~trper is tletlicnted to Professor Htrrry E . G L~I I I I~I I~ 011 the oc.ctr~ioll Of his 65th birth(1tly HEINZ D. ROTH and MARCIA L. MANION SCHILLING. Can. J. Chern. 61, 1027(1983.A series of radical cations has been generated from various cyclopropane derivatives by photoinitiated electron transfcr to chloranil. Nuclcar spin polarization effects observed during these reactions have been interpreted as evidence for the structure of these intermediates. Tri-and tetraalkylsubstituted cyclopropanes (1, 3. 4) form "trirnethylene" radical cations in which the most highly substituted carbon-carbon bond is broken (or weakened). Thc benzocyclopropanorbornene (12) forms a radical cation in which spin and charge are located in the benzenoid ring; the tertiary cyclopropane protons are coupled by a homohyperconjugative interaction; otherwise, the cyclopropane ring is unaffected. To the radical cation derived from bisrnethanoparacyclophane (17) a trirnethylene structure is assigned in which the benzylic carbons are pyramidal. Finally, benzonorcaradiene (20) forms a radical cation in which the two secondary-tertiary bonds are lengthened and in which the rnethylene group bears spin density. Chcrn. 61, 1027Chcrn. 61, (1983.On a produit une sCrie de cations radicalaires a partir de divers derives du cyclopropane en utilisant un transfert d'Clcctron photoinduit sur le chloranil. On a interprCtC les effets de polarisation de spin nucleaire observCs dans ces reactions cornrne une preuve de structure de ces interrnidiaires. Les cyclopropanes portant dcs substituants tri et titraalkylcs (1, 3, 4) forrnent des cations radicalaires "trirnCthylkne" dans lesquels la liaison carbone-carbone la plus substituCe est rornpue (ou affaiblie). Le benzocyclopropanorbornknc (12) forrne un cation radicalaire dans lequel le spin et la chargc sont IocalisCs dans le cycle benzenique; les protons tertiaires du cyclopropane sont couplts par une interaction hornohyperconjuguCe sans quoi le cycle cyclopropane n'est pas affect& Au cation radicalaire provenant du birnCthanoparacyclophane (17) on a attribuk une structure trirnkthylkne dans laquelle les carbones benzyliques sont pyrarnidaux. Finalcrnent le benzonorcaradi2ne (20) forrne un cation radicalaire dans lequel deux liaisons secondaire-tertiaires sont allongees et dans lequel le groupe rnkthylkne porte la densite de spin.[Traduit par le journal]For several years we have been interested in photoinitiated electron transfer reactions and have utilized chemically induced nuclear polarization (CIDNP) effects to gain an insight into the structure and reactivity of short-lived radical cations which can be generated in this type of reaction (1, 2). The CIDNP technique is based on the interpretation of greatly enhanced nmr signals in either absorption or emission, which may be observed during reactions proceeding via pairs of radicals or radical ions (3). According to the generally accepted radical pair theory the dir...

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Section: Norcarene Clerivativessupporting

confidence: 53%

Section: Benzorzo~ca~adiet~ementioning

confidence: 99%

Radical cations of strained ring hydrocarbons. Cyclopropane derivatives

Roth¹,

Schilling²

1983

Can. J. Chem.

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“…acetate. This is illustrated by the lower value of Ei/2 = + 1.51 V (vs. SCE) for the oxidation oitransstilbene compared to a potential of greater than + 2.0 V (vs. SCE) for the oxidation of acetate [14].…”

Section: Discussionmentioning

confidence: 99%

Photoredox Reaction of trans-4-Stilbenecarboxylatopentaamminecobalt(III)

Vogler

Kern

1979

Zeitschrift Für Naturforschung B

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AbstractThe irradiation (λ = 313 nm) of aqueous [Co(III)(NH3)5TSC]2+(TSC-= trans-4-stilbenecarboxylate) leads to a redox reaction with formation of Co2+ as has been shown previously. The TSC-ligand is oxidized to the radical in the primary photoreaction. At higher complex concentrations (～10-2 M) this TSC radical is oxidized to stable products (Φ = 0.09 ± 0.02) by [Co(NH3)5TSC]2+,which is reduced to Co2+ leading to release of the TSC- ligand (Φ = 0.07 ± 0.02). Co2+ is thus formed by both the secondary and the primary photo chemical reaction (Φ overall = 0.16). At low complex concentrations (< 10-4 M) in the presence of air, the primary TSC radical is scavenged by O2. Benz-aldehyde is an oxidation product. This reduces the formation of Co2+ to Φ = 0.09 ± 0.02, which is taken to be the efficiency of the primary photo chemical step. It is suggested that the photoredox reaction is initiated by an electron transfer from the first excited singlet of the TSC- ligand. As shown by sensitization experiments, the population of the lowest TSC-triplet leads to the usual trans/cis isomerization of the TSC-ligand, but not to the redox reaction.

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“…The use of weak nucleophile solvent-supporting electrolyte systems such as HOAc/NaClO 4 drives the reaction to the aliphatic acetate [14], however when the SSE contains a stronger nucleophile: HOAc/NaOAc the obtained product is the arylacetate [15] because once the aromatic cation radical is formed the acetate as nucleophile attacks the ring before any side chain proton is evolved.…”

Section: Resultsmentioning

confidence: 99%