Regiochemistry and mechanism of oxidation ofN-benzyl-N-alkylhydroxylamines to nitrones
摘要:
The oxidation of various N-(o-, m-, p-substituted benzyl)-N-alkylhydroxylamines and their dideuteriobenzyl (PhCD2) counterparts was carried out using mercury(II) oxide and p-benzoquinone (p-BQ) as oxidants. An overwhelming preference for the formation of conjugated nitrones is observed in the oxidation of N-benzyl-N-isopropylhydroxylamines. Considerable intra- and intermolecular kinetic isotope effects and negative rho values in the Hammet plots point towards a mechanistic pathway that involves electron transfer from nitrogen to the oxidant followed by hydrogen abstraction. The conformation of unstable (E)-nitrones, which readily isomerize to the more stable (Z)-nitrones, is deduced from H-1 NMR data. The E = Z isomerization was found to be a bimolecular process. Copyright (C) 2000 John Wiley & Sons, Ltd.
Aliphatic nitro compounds chemistry: oximes–nitrones tunable production through directed tandem synthesis
作者:Foad Kazemi、Moosa Ramdar、Jamal Davarpanah
DOI:10.1007/s00706-018-2326-4
日期:2019.2
AbstractReduction of aliphatic nitro compounds in the presence of aldehydes and dialdehydes for tunable directedsynthesis of oximes, nitrones, nitrone–oximes, and dinitrones was reported. The slow and nonselective reduction of aliphatic nitro compounds was directed by condensation of in situ prepared alkylhydroxylamines with aromatic aldehydes. Mononitrones and dinitrones were synthesized at reflux
摘要据报导,在醛和二醛存在下还原脂肪族硝基化合物可调谐合成肟,硝酮,硝酮肟和二硝基酮。脂肪族硝基化合物的缓慢且非选择性的还原是通过原位制备的烷基羟胺与芳族醛的缩合来实现的。在四氢呋喃中,使用SnCl 2 ·2H 2 O和Na 2 CO 3分别在回流和55°C条件下合成单硝酮和二硝酮。研究发现,当使用二醛作为醛源时,催化量的羧酸(如3-苯基丙酸)的存在相对于硝酮肟和二肟而言,可以提高二硝酮的收率。 图形概要
Access to Nitrones from Amines via Electrocatalysis at Room Temperature
synthesis of nitronesfrom bench stable amines has been developed under constant current electrolysis at room temperature, rendering metal and external oxidant-free protocol in an alkaline medium. The electrocatalysis steps of reported strategy involve anodic oxidation of benzyl amines followed by cathodic reduction of nitro-functional group in an undivided cell affording functional nitrones. The robustness