- Single Electron Transfer in the Reaction of Enolates with Alkyl Halides
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Single electron transfer (SET) in the reaction of a model system consisting of lithiopropiophenone with primary neopentyl type alkyl halides and tosylate was investigated by (1) the use of an appropriate cyclizable alkyl radical probe, (2) observing the effect of varying the leaving group on reaction rate and product distribution, (3) studying the effect of light, di-tert-butyl nitroxyl radical, and p-dinitrobenzene on the rate of reaction, (4) observing the consequence of varying solvent composition on both the reaction rate and product distribution, and (5) studying the effects of the radical traps, dicyclohexylphosphine and 1,4-cyclohexadiene, on product composition.The results of these studies indicate that single electron transfer is the major reaction pathway involved in the reaction of the enolate with the alkyl iodide in HMPA and that the corresponding bromide and tosylate react by an SN2 process.
- Ashby, E. C.,Argyropoulos, J. N.
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p. 3274 - 3283
(2007/10/02)
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- EVIDENCE FOR SINGLE ELECTRON TRANSFER IN THE REACTION OF ALKOXIDES WITH ALKYL HALIDES
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Evidence for a radical process in the reaction of lithium alkoxides with alkyl iodides was obtained by observation of cyclization of appropriate radical probes, by the trapping of radicals, and by EPR spectroscopic observations relating to the one electron donor properties of alkoxides.
- Ashby, E. C.,Bae, Dong-Hak,Park, Won-Suh,Depriest, Robert N.,Su, Wei-Yang
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p. 5107 - 5110
(2007/10/02)
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- EVIDENCE FOR SINGLE ELECTRON TRANSFER IN THE REACTION OF A LITHIUM ENOLATE WITH A PRIMARY ALKYL IODIDE
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Evidence for a radical process in the reaction of the lithium enolate of propiophenone with a primary alkyl iodide was obtained by the observation of cyclization of an appropriate radical probe, by the trapping of the radical intermediate and by the comparison of the relative rates of reactions of the probe alkyl iodide with the corresponding bromide and tosylate.
- Ashby, E.C.,Argyropoulos, J.N.
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- Organometallic Reaction Mechanisms. 17. Nature of Alkyl Transfer in Reactions of Grignard Reagents with Ketones. Evidence for Radical Intermediates in the Formation of 1,2-Addition Product Involving Tertiary and Primary Grignard Reagents
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When a Grignard reagent reacts with an aromatic ketone, a radical anion-radical cation pair is formed which can collapse to give 1,2-addition product or dissociate to form a radical anion and a free radical within the solvent cage which in turn can collapse to 1,2-addition product or a conjugate addition product or escape the solvent cage to form pinacol.The 1,2-addition products, which form after dissociation of the radical anion-radical cation pair, show free-radical character as indicated by the cyclized 1,2-addition products formed from the reaction of a tertiary Grignard reagent probe with benzophenone in THF and from the reaction of a primary Grignard reagent probe (neooctenyl Grignard reagent) with benzophenone in ether.The 1,6-addition products, which come about after dissociation of the radical anion-radical cation pair, show free-radical character as evidenced by the cyclized 1,6-addition products formed in all of the reactions which involve the tertiary probe Grignard reagent (in all solvents studied) with benzophenone and 2-MBP and also in the reaction of the neooctenyl probe Grignard reagent with 2-MBP.
- Ashby, E. C.,Bowers, Joseph R.
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p. 2242 - 2250
(2007/10/02)
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- Evidence for Single Electron Transfer in the Reactions of Alkali Metal Amides and Alkoxides with Alkyl Halides and Polynuclear Hydrocarbons
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Evidence for single electron transfer as the major pathway in reactions previously considered to be classic SN1 and SN2 pathways has been obtained.In this connection, the reaction of KOBu-t with trityl bromide has been shown to proceed through the trityl radical, and the reaction of LiN(i-Pr)2 with a primary alkyl iodide probe gave evidence of proceeding by single electron transfer, as indicated by the cyclized nature of the product as a result of a radical intermediate.
- Ashby, E. C.,Goel, A. B.,DePriest, R. N.
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p. 2429 - 2431
(2007/10/02)
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