Bi(I)-Catalyzed Transfer-Hydrogenation with Ammonia-Borane
作者:Feng Wang、Oriol Planas、Josep Cornella
DOI:10.1021/jacs.9b00594
日期:2019.3.13
transfer-hydrogenation utilizing a well-defined Bi(I) complex as catalyst and ammonia-borane as transfer agent has been developed. This transformation represents a unique example of low-valent pnictogen catalysis cycling between oxidation states I and III, and proved useful for the hydrogenation of azoarenes and the partial reduction of nitroarenes. Interestingly, the bismuthinidene catalyst performs
已经开发了利用明确定义的 Bi(I) 配合物作为催化剂和氨硼烷作为转移剂的催化转移氢化。这种转变代表了氧化态 I 和 III 之间的低价色素原催化循环的独特例子,并被证明可用于偶氮芳烃的氢化和硝基芳烃的部分还原。有趣的是,铋烯催化剂在低价过渡金属敏感官能团的存在下表现良好,并且与类似的磷基催化相比表现出正交反应性。机理研究表明,一种难以捉摸的铋物种的中间体,被认为是氢化和氢形成的原因。
Hypercrosslinked Polymer Platform-Anchored Single-Site Heterogeneous Pd–NHC Catalysts for Diverse C–H Functionalization
作者:Tanmoy Mandal、Moumita Mondal、Joyanta Choudhury
DOI:10.1021/acs.organomet.1c00182
日期:2021.8.9
new class of hypercrosslinked polymer (HCP) platform-anchored single-site heterogenized Pd–NHC catalysts for multipurpose C–H functionalization reactions. This new class is represented by a set of three catalysts, viz., HCP-B-MeNHC-Pd, HCP-B-BnNHC-Pd, and HCP-TPM-MeNHC-Pd, having a variation on the structural feature of the anchoring polymeric platform. All three catalysts were fully characterized via
我们展示了一类新的超交联聚合物(HCP)平台锚定的单点异质化 Pd-NHC 催化剂,用于多用途 C-H 功能化反应。这一新类别由一组三种催化剂代表,即HCP-B- Me NHC-Pd、HCP-B- Bn NHC-Pd和HCP-TPM- Me NHC-Pd,在结构特征上有变化锚定聚合物平台。所有三种催化剂都通过各种固态表征和分析技术(如 X 射线光电子能谱、13C 交叉极化魔角自旋核磁共振、场发射扫描电子显微镜、能量色散 X 射线分析、热重分析和电感耦合等离子体-光发射光谱法。三种经常使用且非常有用的 C-H 官能化反应,即 C-H 卤化、乙酰氧基化和芳基化,用新催化剂进行了测试,发现它们具有高度的相容性和成功性。使用HCP-TPM- Me NHC-Pd在催化剂的作用下,卤化、乙酰氧基化和芳基化反应的官能化产物的产率分别高达 85%、75% 和 70%。这种新系统提供了诸如增强的活性、异质性和可回收性等苛刻的特性,使其成为非均相
Photocatalyzed oxidative dehydrogenation of hydrazobenzenes to azobenzenes
作者:Haiping Lv、Ronibala Devi Laishram、Jiayan Li、Yongyun Zhou、Dandan Xu、Sagar More、Yuze Dai、Baomin Fan
DOI:10.1039/c9gc01235d
日期:——
Visible light mediated oxidativedehydrogenation of hydrazobenzenes under an ambient atmosphere using an organic dye as a photocatalyst was reported for the first time. The reaction provides an environmentally benign method for the preparation of azobenzenes in excellent yields with good functional group tolerance.
Synthesis of phenazines from ortho-bromo azo compounds via sequential Buchwald-Hartwig amination under micellar conditions and acid promoted cyclization
amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π-electrocyclization-aromatization process. Two different synthetic pathways to obtain the ortho-bromo azo intermediates were explored, namely the palladium catalysed selective ortho bromination of azobenzenes and the diazo coupling
A metal-free direct oxidative dehydrogenation approach for the synthesis of azobenzenesfrom hydrazobenzenes has been developed by using TEMPO as an organocatalyst for the first time. The reaction proceeded in open air under mild reaction conditions. A wide range of hydrazobenzenes readily undergo dehydrogenation to give the corresponding azobenzenes in excellent yields.