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
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。
Acceptorless Dehydrogenative Cross-Coupling of Primary Alcohols Catalyzed by an N-Heterocyclic Carbene–Nitrogen–Phosphine Chelated Ruthenium(II) Complex
The acceptorless dehydrogenativecross-coupling of primaryalcohols to form cross-esters with the liberation of H2 gas was enabled using a [RuCl(η6-C6H6)(κ2-CNP)][PF6]Cl complex as the catalyst. This sustainable protocol is applicable to a broad range of primaryalcohols, particularly for the sterically demanding ones, featuring good functional group tolerance and high selectivity. The good catalytic
使用 [RuCl(η 6 -C 6 H 6 )(κ 2 -CNP)][PF 6 ]Cl 络合物,可以实现伯醇的无受体脱氢交叉偶联以形成交叉酯并释放 H 2气体催化剂。这种可持续的协议适用于广泛的伯醇,特别是对于空间要求高的伯醇,具有良好的官能团耐受性和高选择性。良好的催化性能可归因于氮-膦功能化的N-杂环卡宾(CNP)配体,它采用面配位模式以及配位苯的容易解离。
The effect of<i>para</i>-substitution on the mass spectra of arylsulphonate esters of neopentanol
作者:Orval A. Mamer、Abeysinghe A. Padmapriya、George Just
DOI:10.1002/oms.1210201210
日期:1985.12
AbstractThe mass spectra of several para‐substituted benzenesulfonic and benzoic esters of unlabelled and 1,1‐d2‐neopentyl alcohol are examined and compared. Evidence is presented of migration of the aryl group from the sulfur to an oxygen atom in the molecular ions of the sulfonic esters. The nature of the fragmentation processes and the occurrence of metastable ions for these processes are both much more dependent upon the polarity of the para substituent in the case of the sulfonates than for the benzoates. Elimination of C5H10 occurs from the molecular ion of the p‐methoxysulfonate with transfer to the residual ion of a hydrogen atom selected randomly from the alkyl fragment, while in the case of the p‐aminosulfonate, incomplete randomization is demonstrated.
Caron, Stephane; Hawkins, Joel M., Journal of Organic Chemistry, 1998, vol. 63, # 7, p. 2053 - 2055