两种新型的钌络合物期RuH(CO)氯(PPH 3)(κ 2 -CP)(1)和[ FAC -RuH(CO)(PPH 3)(κ 3 -CNP)]氯(2)轴承不对称ñ -杂环合成了卡宾-氮-膦(CNP)并通过1 H NMR,31 P NMR和HRMS进行了表征。配合物2的结构通过单晶X射线衍射进一步确认。阴离子交换实验证明复合物2可以转化为复合物1在解决方案中。两种络合物在醇与酯的无受体脱氢偶联中显示出高催化性能,并且在对-和间-取代的苄醇和长链伯醇的催化剂负载量为1%时,酯的分离产率极佳。尽管由于空间位阻以及电子给体与钌中心的配位,一些邻位取代的苄醇显示出较低的反应性,但延长反应时间仍可获得良好的产物收率。特别地,该系统成功地实现了两种不同伯醇之间的酯的脱氢交叉偶联。
Cobalt-Catalyzed Acceptorless Dehydrogenative Coupling of Primary Alcohols to Esters
作者:Keshav Paudel、Bedraj Pandey、Shi Xu、Daniela K. Taylor、David L. Tyer、Claudia Lopez Torres、Sky Gallagher、Lin Kong、Keying Ding
DOI:10.1021/acs.orglett.8b01775
日期:2018.8.3
A novel catalytic system with a tripodal cobalt complex is developed for efficiently converting primaryalcohols to esters. KOtBu is found essential to the transformation. A preliminary mechanistic study suggests a plausible reaction route that involves an initial Co-catalyzed dehydrogenation of alcohol to aldehyde, followed by a Tishchenko-type pathway to ester mediated by KOtBu.
为了有效地将伯醇转化为酯,开发了具有三脚架钴络合物的新型催化体系。KO t Bu被发现对转型至关重要。初步的机理研究表明,可能的反应路线包括最初的共催化将醇脱氢成醛,然后由Tishchenko型途径由KO t Bu介导生成酯。
N‐Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O‐containing compounds. Demonstrated here is a novel N‐heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O‐atomsfromO2. Mechanistic studies prove that
Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
作者:Xiaolin Jiang、Jiahui Zhang、Dongmei Zhao、Yuehui Li
DOI:10.1039/c8cc10315a
日期:——
ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted
Nickel-catalyzed Tishchenko reaction via hetero-nickelacycles by oxidative cyclization of aldehydes with nickel(0) complex
作者:Sensuke Ogoshi、Yoichi Hoshimoto、Masato Ohashi
DOI:10.1039/b926866a
日期:——
A Ni(0)-catalyzed Tishchenko reaction which can be applied to a variety of aliphatic aldehydes (1°, 2°, 3°) and aromatic aldehydes was developed. The reaction might proceed via a hetero-nickelacycle intermediate.
An environmentally benign solvent-free Tishchenko reaction
作者:Daniel C. Waddell、James Mack
DOI:10.1039/b810714a
日期:——
Herein, we describe the solvent-free ball milling Tishchenko reaction. Using high speed ball milling and a sodium hydride catalyst, the Tishchenko reaction was performed for aryl aldehydes in high yields in 0.5 hours. The reaction is not affected by the type of ball bearing used and can be successful when conducted in a liquid nitrogen environment.