Aliphatic semidiones.  V.  Radical anions derived from vicinal triketones

Russell, Glen A.; Weiner, Steven A.

doi:10.1021/ja01001a040

Cited by 26 publications

(26 citation statements)

References 1 publication

(1 reference statement)

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“…The line indicated in Figure 25 fits the equation E1/2 =-1.92-4.3jS. This is not very con sistent with the slope of 2.5 previously reported for one electron reductions (6,74). Such correlations are expected spin density.…”

Section: B" O2supporting

confidence: 69%

“…Those "quinones" or diketones which have a dicarbonyl moiety conjugated with an aromatic system, but which have no possibility for achieving aromaticity upon reduction, have even greater negative re duction potentials. This class of compounds includes acenaphthenequinone (3) and benzil (6) which have reduction potentials intermediate in magnitude between those of potentially aromatic quinones and those of aliphatic di ketones such as biacetyl (6). The presence of a diketo group…”

Section: R ^Oh Y-h 0=0mentioning

confidence: 99%

“…Some aromatic semidiones which have been studied by ESR are those derived from benzocyclobutenedione (16), acenaphthenequinone (I7), benzil {Vj), 1-phenylpropane-1,2-dione (18) and furil (19). Some reported aromatic semitriones are those derived from ninhydrin (20) ami 1, -di f/iienylpropanetrione (6). The examples of semidiones or semitriones which have heteroatoms bonded to the dicarbonyl moiety are the radical anions of ethyl benzoylformate (I8), the mesoxalate esters (6), 1-benzoxalate (6) and alloxan (20).…”

Section: Ch3cococh3mentioning

confidence: 99%

“…The order of aromatic proton splittings for both series of compounds is N >0 > S, with the greater difference between oxygen and sulfur. ^Reference (6).…”

Section: Gauss Gaussmentioning

confidence: 99%

“…The data used are shown in Table X. Such correlations have been used in previous ESR work to justify parameters used in molecular orbital calculations (6,11,74). In the isatin series the Table IX. calculation predicts smaller differences than those observed experimentally.…”

Section: B" O2mentioning

confidence: 99%

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Aromatic and heterocyclic semidiones

Myers

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Section: B" O2supporting

confidence: 69%

Section: R ^Oh Y-h 0=0mentioning

confidence: 99%

Section: Ch3cococh3mentioning

confidence: 99%

“…The order of aromatic proton splittings for both series of compounds is N >0 > S, with the greater difference between oxygen and sulfur. ^Reference (6).…”

Section: Gauss Gaussmentioning

confidence: 99%

Section: B" O2mentioning

confidence: 99%

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Aromatic and heterocyclic semidiones

Myers

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Radikal‐Anionen als Zwischenstufen in der Organischen Chemie

Holy

Marcum

1971

Angewandte Chemie

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SchluBDie Zahl der Arbeiten, in denen systematisch der EinfluR der Liganden auf die katalytische Aktivitat eines u b e rgangsmetall-Katalysators untersucht wurde, ist noch verhaltnisma8ig klein. Solange eine breite experimentelle Basis fehlt, ist sicher auch eine gelegentliche Fehlinterpretation nicht ganz auszuschlieRen. In diesem Sinne sei dieser Fortschrittsbericht in erster Linie als Anregung verstanden. Es ware uns eine Genugtuung, wenn durch ihn hier und dort systematische Forschung initiiert wurde, die das Verstandnis dieser fur das gesamte Gebiet der Katalyse an ubergangsmetallen so wichtigen Zusammenhange vertiefen helfen konnte.

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Radical Anion Intermediates in Organic Chemistry

Holy

Marcum

1971

Angew. Chem. Int. Ed. Engl.

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The two isomeric cyclopropane derivatives (34) and (35) are formed in a yield of 30-70% together with diethyl fumarate and diethyl maleate. The ratio of ex0 compound to endo compound depends on the substituent R in the phosphite ligand, and decreases as R varies inThis result is interpreted by Moser as follows. The better the acceptor properties of the phosphite ligand on the copper, the greater is the positive charge on the metal, and the stronger, therefore, is the bonding with all the other ligands. The decrease in the bond lengths leads to steric hindrance between the reactant (coordinated cyclohexene) and the phosphite ligand. It is plausible on the basis of a model of the transition state, that this will favor the formation of the endo form.For the 0-and m-substituted phenyl phosphites, a linear relation exists between the ratio log(exo/endo) and the Hammett B values for the substituents R. This indicates that the effects observed are purely electronic in origin. Nevertheless, they ultimately act via the steric hindrance of one of the two possible transition states. The author speaks of stereo-electronic effect. In the case of o-substitution, the values found for (exo/endo) are lower than those expected from the Hammett lines. This purely steric effect shows again that steric hindrance places the ex0 form (34) at a disadvantage in relation to the endo form (35). ConclusionThe number of systematic studies that have been carried out on the influence of the ligands on the catalytic activity of a transition metal catalyst is still relatively small. As long as a broad experimental basis is lacking, one cannot entirely rule out the possibility of occasional misinterpretations. In this sense, the present review is intended mainly to stimulate interest. We would be content if it led to the initiation of a few systematic studies that might help to deepen our understanding of these relationships, which are so important to the entire field of catalysis on transition metals.

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Aliphatic semidiones. V. Radical anions derived from vicinal triketones

Cited by 26 publications

References 1 publication

Aromatic and heterocyclic semidiones

Aromatic and heterocyclic semidiones

Radikal‐Anionen als Zwischenstufen in der Organischen Chemie

Radical Anion Intermediates in Organic Chemistry

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