Methylenecyclopropane rearrangement as a probe for free radical substituent effects. .sigma..bul. Values for commonly encountered conjugating and organometallic groups

Creary, Xavier; Mehrsheikh-Mohammadi, M. E.; McDonald, Steven R.

doi:10.1021/jo00391a015

Cited by 151 publications

(111 citation statements)

References 2 publications

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“…This clearly demonstrates that a build-up of positive charge takes place in the step involving substrate activation. There is no correlation with Creary's r • -values [20], which rules out the involvement of a benzyl radical in this reaction.…”

Section: Discussionmentioning

confidence: 80%

Mechanistic Investigation of the Gold-catalyzed Aerobic Oxidation of Alcohols

2007

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The mechanism for the gold-catalyzed aerobic oxidation of alcohols was studied using a series of parasubstituted benzyl alcohols (Hammett methodology). The competition experiments clearly show that the rate-determining step of the reaction involves the generation of a partial positive charge in the benzylic position (i.e. hydride abstraction). This was further substantiated by the determination of a significant kinetic isotope effect (k H / k D = 1.41), when employing an alcohol substrate deuterated in this position.

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Section: Discussionmentioning

confidence: 80%

Mechanistic Investigation of the Gold-catalyzed Aerobic Oxidation of Alcohols

2007

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“…Rather, the observed dependence is diagnostic for a radical-stabilizing effect, since both electron-donating and -withdrawing para substituents are known to stabilize the benzylic radicals, 24 which are being produced by decarbonylation (Scheme 2). Indeed, the Creary scale for radical substituent effects, 25 which we have employed in the quantitative analysis of the deazatization rate constants of phenylazomethanes (right-hand in Scheme 3), 26 predicts the selected aryl substituents to be radical stabilizing (cf. positive s rad values in Table 1); the p-CF 3 group displays the weakest radical-stabilizing effect.…”

Section: Substituent Effectsmentioning

confidence: 99%

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Zhang

Nau

2000

J. Phys. Org. Chem.

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“…First, most substituents do not have a large effect on radical stabilities. Whereas they might have multifold effects on relative rates of radical reactions, it translates into small (0-3 kcal/mol) [17,[20][21][22][23][24][25][26], in energy lowering. Even ''super radical stabilizers'' [25], such as 4-pyridinyl-n-oxide or 2-furyl have modest effects (ca.…”

Section: Introductionmentioning

confidence: 99%

“…Either mechanism accounts for the presence of triplet ground states in non-disjoint diradicals such as TMM [15,16], m-xylylene [32,33], and a,2-and a,4-dehydrotoluene [34,35], and singlet ground states in disjoint diradicals such as TME [22,23], square cyclobutadiene [24], planar D 8h cyclooctatetraene [28,36], and a,3-dehydrotoluene [34,35]. The substituent effect on the singlet-triplet splittings in aromatic nitrenes is also manifestation of the same effect.…”

Section: Introductionmentioning

confidence: 99%