chromium-catalyzed activation of acyl C–O bonds with magnesium for amidation of esters with nitroarenes. Low-cost chromium(III) chloride shows high reactivity in promoting amidation by using magnesium as reductant and chlorotrimethylsilane as additive. It provides a step-economic strategy to the synthesis of centrally important amide motifs using inexpensive and air-stable nitroarenes as amino sources.
amidation of unactivated esters with amines under transition-metal-free and solvent-freeconditions, affording a series of amides in good to excellent yields at room temperature. In particular, an environmentally friendly and practical workup procedure, which circumvents the use of organic solvents and chromatography in most cases, was disclosed. Moreover, the gram-scale production of representative products
在本文中,开发了一种NaO t Bu介导的合成方法,用于在无过渡金属和无溶剂的条件下将未活化的酯与胺直接酰胺化,从而在室温下以良好或优异的收率提供了一系列酰胺。特别地,公开了一种环境友好且实用的后处理程序,其在大多数情况下避免了有机溶剂和色谱的使用。此外,代表产品3a,3w和3au的克级生产通过应用操作简单,可持续和实用的程序有效地实现了这一目标。此外,该方法也适用于有价值的分子的合成,例如莫氯贝胺(一种强效抗抑郁药),苯达尼尔和芬呋喃(两种市售农业杀菌剂)。这些结果表明该方案具有简化工业中酰胺合成的潜力。同时,对所有目标产品的定量绿色指标进行了评估,这表明本协议在环境友好性和可持续性方面优于已报道的协议。最后,还进行了额外的实验和计算计算,以阐明这种转换的机理见解,
Highly efficient dehydrogenative cross-coupling of aldehydes with amines and alcohols
作者:Ramesh Deshidi、Masood Ahmad Rizvi、Bhahwal Ali Shah
DOI:10.1039/c5ra17425b
日期:——
A common protocol for the synthesis of amides, esters and α-ketoesters via cross dehydrogenative coupling of aldehydes and amines/alcohols has been developed.
通过醛和胺/醇的交叉脱氢偶联合成酰胺、酯和α-酮酯的常见协议已经开发出来。
Catalyst- and Supporting-Electrolyte-Free Electrosynthesis of Benzothiazoles and Thiazolopyridines in Continuous Flow
作者:Ana A. Folgueiras-Amador、Xiang-Yang Qian、Hai-Chao Xu、Thomas Wirth
DOI:10.1002/chem.201705016
日期:2018.1.9
N‐arylthioamides have been converted to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte‐free reaction, (ii) an easy scale‐up
Exogenous Photosensitizer-, Metal-, and Base-Free Visible-Light-Promoted C–H Thiolation via Reverse Hydrogen Atom Transfer
作者:Ze-Ming Xu、Hong-Xi Li、David James Young、Da-Liang Zhu、Hai-Yan Li、Jian-Ping Lang
DOI:10.1021/acs.orglett.8b03679
日期:2019.1.4
This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydrogen-atom transfer (RHAT) with 2,2,6,6-tetramethylpiperidineN-oxyl to form a sulfur radical. The addition of the sulfur radical to the benzene ring gives an aryl radical, which then rearomatizes to benzothiazole via RHAT.