A Concerted Transfer Hydrogenolysis: 1,3,2-Diazaphospholene-Catalyzed Hydrogenation of NN Bond with Ammonia-Borane
作者:Che Chang Chong、Hajime Hirao、Rei Kinjo
DOI:10.1002/anie.201400099
日期:2014.3.24
1,3,2‐diazaphospholenescatalyzemetal‐free transfer hydrogenation of a NN double bond using ammonia–borane under mild reaction conditions, thus allowing access to various hydrazine derivatives. Kinetic and computational studies revealed that the rate‐determining step involves simultaneous breakage of the BH and NH bonds of ammonia–borane. The reaction is therefore viewed as a concerted type of
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。
TEMPO catalyzed oxidative dehydrogenation of hydrazobenzenes to azobenzenes
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.
Visible-Light-Promoted Hydrogenation of Azobenzenes to Hydrazobenzenes with Thioacetic Acid as the Reductant
作者:Qiao Li、Yanshu Luo、Jianhui Chen、Yuanzhi Xia
DOI:10.1021/acs.joc.2c02873
日期:2023.2.17
A catalyst- and metal-free hydrogenation of azobenzenes to hydrazobenzenes in the presence of thioaceticacid was achieved under visible light irradiation. The transformation was carried out under mild conditions in an air atmosphere at ambient temperature, generating a variety of hydrazobenzenes with yields up to 99%. The current process is compatible with a variety of substituents and is highly chemoselective
Cobalt-catalyzed borylative reduction of azobenzenes using pinacolborane is developed. The simple cobalt chloride catalyst and reaction conditions make this protocol attractive for hydrazobenzene synthesis. This borylative reduction shows good functional group compatibility and can be readily scaled up to the gram scale. Preliminary mechanistic studies clarified the proton source of the hydrazine products