- A new synthetic approach for novel 4-substituted-5-nitroimidazoles
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A new synthetic approach, involving an SRN1 reaction of the anion of 1-methyl-4-phenylsulfonyl-methyl-5-nitro-1H-imidazole with 2,2-dinitropropane and a radical anion or a concerted radical reductive elimination of sulfonyl and nitro groups affords an original 5-nitroimidazole bearing a trisubstituted ethylenic double bond at 4-position.
- Crozet, Maxime D.,Perfetti, Patricia,Kaafarani, Mustapha,Vanelle, Patrice,Crozet, Michel P.
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p. 4127 - 4129
(2007/10/03)
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- Cleavage reactions of radical anions that range from homolytic to heterolytic within the same family of compounds
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Properties of the radical anions of three α-nitrocumenes, (α-nitrocumene, p-cyano-α-nitrocumene, and p-nitro-α-nitrocumene, 1a-c) have been determined by electrochemical methods. In particular, the standard potentials of the neutral/radical anion couples were found to be -2.20, -2.04, and -1.43 V with respect to the ferrocenium ion/ferrocene potential and the rate constants for expulsion of nitrite from the radical anions were 3 × 106, 5 × 106, and 240 s-1 for 1a-c, respectively. Comparison of these potentials with those of related compounds demonstrates that reduction of the nitroalkyl portion of the molecule occurs in 1a and 1b while in 1c the electron is added to the nitrophenyl group. Thus, using previously defined terminology, the cleavage of the radical anions of 1a and 1b to give nitrite and the corresponding cumyl radicals are examples of homolytic cleavage reactions but the cleavage of the radical anion of 1c is heterolytic. The driving force for the three cleavage reactions has been estimated and it is concluded that the large decrease in magnitude of the cleavage rate constants on going from 1a and 1b to 1c is mainly due to the much larger driving force for the first two.
- Zheng, Zi-Rong,Evans, Dennis H.,Chan-Shing, Elisa Soazara,Lessard, Jean
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p. 9429 - 9434
(2007/10/03)
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- A facile preparation of dialkyl phosphonate compounds from sterically hindered p-nitrocumyl halides through the S(RN)1 mechanism
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p-Nitrobenzyl phosphonate anion with p-nitrocumyl halides gives a good yield of the coupling product dialkyl[(1,1-dimethyl-1,2-di-(p- nitrobenzyl)ethyl] phosphonates through the S(RN)1 mechanism. The reaction was greatly accelerated by sunlamp irradiation but inhibited by the radical scavenger (t-Bu)2NO..
- Rhee, Jong Uk,Russell, Glen A.,Baik, Woonphil
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p. 8601 - 8604
(2007/10/03)
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- Electron-transfer substitution reactions: The p-nitrocumyl system
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Facile substitution reactions at the tertiary carbon of p-nitrocumyl chloride and α,p-dinitrocumene are described. These reactions occur with a wide range of organic and inorganic nucleophiles and are noteworthy for providing novel and powerful means of synthesis; they occur readily under mild conditions, give excellent yields of pure products, and, in contrast to SN2 displacements, are rather insensitive to steric hindrance. They are, therefore, especially valuable for the preparation of highly branched compounds. The view that these are electron-transfer chain processes derives from inhibition studies and, also, from the fact that these reactions are induced by one-electron-transfer agents.
- Kornblum, Nathan,Cheng, Leung,Davies, Thomas M.,Earl, Gary W.,Holy, Norman L.,Kerber, Robert C.,Kestner, Melvin M.,Manthey, Joseph W.,Musser, Michael T.,Pinnick, Harold W.,Snow, Donald H.,Stuchal, Francis W.,Swiger, Roger T.
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p. 196 - 204
(2007/10/02)
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- REACTIVITY OF HETEROCYCLIC AMBIENT S...N ANIONS IN SRN1 SUBSTITUTION REACTIONS
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Ambident anions of 2-mercaptoazoles react, under photo- stimulation conditions, with α,p-dinitrocumene according to an SRN1 mechanism (short chain) leading to S-alkylated compounds in agreement with a kinetically controlled reaction.Regioselect
- Meyer, Monique,Samat, Andre,Chanon, Michel
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p. 1013 - 1018
(2007/10/02)
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