The synthesis of azoacetylenes (=dialkynyldiazenes) 1 and 2 has been investigated. They represent a still elusive class of chromophores with potentially very interesting applications as novel bistable photochemical molecular switches or as antitumor agents (Fig. 1). Our synthetic efforts have led us alongside three different approaches (Scheme 1). In a first route, it was envisioned to generate the
A highly efficient, metal-free, chemical oxidation of hydrazines has been implemented using environmentally friendly TCCA as oxidant. This benign protocol provides straightforward access to a wide range of azo compounds in THF in excellent yield. Altogether, 35 azo compounds were obtained in this way and scale-up preparations were performed. Additionally, a plausible mechanism was also proposed. Step-economical
Cobalt-Catalyzed Regioselective <i>para</i>-Amination of Azobenzenes via Nucleophilic Aromatic Substitution of Hydrogen
作者:Yigao Tao、Rong Hu、Zeyu Xie、Ping Lin、Weiping Su
DOI:10.1021/acs.joc.2c00026
日期:2022.4.1
The metal-catalyzed nucleophilic aromatic substitution of hydrogen (SNArH) via coordination of the substituent on the aromatic ring to the metal catalyst, in terms of reactivity, substrate type, and reaction selectivity, complements the transition metal-catalyzed C–H functionalization that proceeds via C–H metalation but remains an elusive target. Described herein is the development of an unprecedented
通过芳环上的取代基与金属催化剂的配位,金属催化的氢的亲核芳族取代 (S N ArH) 在反应性、底物类型和反应选择性方面,补充了过渡金属催化的 C-H 官能化通过 C-H 金属化进行,但仍然是一个难以捉摸的目标。本文描述了一种前所未有的钴催化偶氮苯对位选择性胺化的发展,其本质上是由 Hammett 分析揭示的金属促进的 S N ArH 过程,从而说明了芳烃环上的取代基与金属催化剂可能导致芳烃环向 S N亲电活化氩气。这种钴催化的方案允许使用多种脂肪胺和苯胺作为胺化试剂,耐受偶氮苯的电子多样化取代基,并以良好的产率提供相应的产品,并对对胺化具有区域特异性选择性。
Visible-light-promoted decarboxylative addition cyclization of <i>N</i>-aryl glycines and azobenzenes to access 1,2,4-triazolidines
作者:Jingya Yang、Menghui Song、Hongyan Zhou、Yanfang Qi、Ben Ma、Xi-Cun Wang
DOI:10.1039/d1gc02272e
日期:——
Direct synthesis of 1,2,4-triazolidines have been readily achieved by the visible-light-promoted reaction of N-aryl glycines and azobenzenes under mild conditions.
在温和的条件下,通过可见光促进的反应,N-芳基甘氨酸和偶氮苯可以直接合成1,2,4-三唑啉。
Visible‐Light‐Driven Hydrophosphorylation of Azobenzenes Enabled by
<i>trans</i>
‐to‐
<i>cis</i>
Photoisomerization
作者:Jingya Yang、Cunhui Wang、Hongyan Zhou、Qianqian Kong、Wentong Ma
DOI:10.1002/adsc.202201089
日期:2022.12.20
visible-light-driven hydrophosphorylation of azobenzenes with diarylphosphine oxides was successfully developed. The reaction proceeded smoothly under blue light irradiation at room temperature without any photocatalyst required, providing a mild approach for this transformation with new strategy. Of important note is that the visible light-driven trans-to-cis photoisomerization of azobenzenes was found to