- Electrodimerization ofN-Alkoxyamides for the Synthesis of Hydrazines
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An efficient and valuable N-N dimerization reaction ofN-alkoxyamides is reported under undivided electrolytic conditions. This electrochemical strategy provides a powerful way to access a wide range of advanced, highly functionalized hydrazines. Remarkably, anN-centered radical generated from the cleavage of the N-H bond under electrolytic conditions plays a crucial role in this transformation. Furthermore, variousN-alkoxyamides bearing different substituents are suitable in this transformation, furnishing the corresponding hydrazines in up to 92% yield.
- Nasier, Abudulajiang,Chang, Xihao,Guo, Chang
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p. 16068 - 16076
(2021/09/18)
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- Reaction of N-acyloxy-N-alkoxyamides with biological thiol groups
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Mutagenic N-acyloxy-N-alkoxyamides 1 react with thiols by an SN2 process at nitrogen with displacement of carboxylate. They react with glutathione 4 in [D6]DMSO/D2O and methyl and ethyl esters of cysteine hydrochloride, 11 and 12, in [D4]methanol but the intermediate N-alkoxy-N-(alkylthio)amides undergo a rapid substitution reaction at sulfur by a second thiol molecule to give hydroxamic esters and disulfides. Arrhenius activation energies and entropies of activation obtained for a series of different N-benzyloxy-N-(4-substitutedbenzoyloxy)benzamides 13-17 were similar to those found for the SN2 reaction of the same series with N-methylaniline. Entropies of activation were strongly negative in keeping with polar separation and attendant solvation in the transition state, and in keeping with this, bimolecular reaction rate constants at 298K correlated with Hammett σ constants with a positive ρ-value of 1.1. The structure of model N-methoxy-N-(methylthio)acetamide has been computed at the B3LYP/6-31G(d) level and exhibits properties atypical of other anomeric amides with more electronegative atoms at nitrogen. Relative to N,N-bisoxyl substitution, the combination of a sulfur and an oxygen atom at the amide nitrogen results in a relatively small reduction in amide resonance.
- Glover, Stephen A.,Adams, Meredith
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experimental part
p. 443 - 453
(2011/10/09)
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- Evidence for the Formation of Nitrenium Ions in the Acid-catalysed Solvolysis of Mutagenic N-Acetoxy-N-Alkoxybenzamides
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In aqueous acetonitrile, N-acetoxy-N-alkoxybenzamides undergo acid-catalysed solvolysis by the AAl1 mechanism to give acetic acid and nitrenium ions.This is indicated by an inverse dependence of the acid-independent rate constant, kH, upon the activity of water, a solvent kinetic isotope effect of 0.44 and positive Σ(excit.) values.In addition, relief of steric compression at the nitrogen enhances the rate of solvolysis.Hammett correlations with ?+ substituent constants were found for the rates of solvolysis of para-substituted-N-acetoxy-N-butoxybenzamides and N-acetoxy-N-(para-substituted benzyloxy) benzamides.This fact and the low ρ-values of -1.35 and -1.56, respectively, are indicative of a strong build-up of positive charge in the transition state which has both nitrenium ion and oxonium ion character and is in accordance with computed molecular-orbital properties of N-alkoxynitrenium ions.Greater levels of mutagenicity have been measured for those compounds which are more readily solvolysed to nitrenium ions.
- Campbell, John J.,Glover, Stephen A.,Hammond, Gerard P.,Rowbottom, Colleen A.
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p. 2067 - 2080
(2007/10/02)
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