Synthesis of Unsymmetrical <i>N</i>-Heterocyclic Carbene–Nitrogen–Phosphine Chelated Ruthenium(II) Complexes and Their Reactivity in Acceptorless Dehydrogenative Coupling of Alcohols to Esters
作者:Xiaochun He、Yaqiu Li、Haiyan Fu、Xueli Zheng、Hua Chen、Ruixiang Li、Xiaojun Yu
DOI:10.1021/acs.organomet.9b00071
日期:2019.4.22
dehydrogenative coupling of alcohols to esters, and the excellent isolated yields of esters were given in a catalyst loading of 1% for para- and meta-substituted benzyl alcohols and long-chain primary alcohols. Although some ortho-substituted benzyl alcohols displayed a relatively low reactivity due to the steric hindrance and the coordination of electron donor with the ruthenium center, the good product
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。