959313-37-2Relevant academic research and scientific papers
Synthesis of Unsymmetrical N-Heterocyclic Carbene-Nitrogen-Phosphine Chelated Ruthenium(II) Complexes and Their Reactivity in Acceptorless Dehydrogenative Coupling of Alcohols to Esters
He, Xiaochun,Li, Yaqiu,Fu, Haiyan,Zheng, Xueli,Chen, Hua,Li, Ruixiang,Yu, Xiaojun
, p. 1750 - 1760 (2019/04/17)
Two novel ruthenium complexes RuH(CO)Cl(PPh3)(κ2-CP) (1) and [fac-RuH(CO)(PPh3)(κ3-CNP)]Cl (2) bearing unsymmetrical N-heterocyclic carbene-nitrogen-phosphine (CNP) were synthesized and characterized with 1H NMR, 31P NMR, and HRMS. The structure of complex 2 was further confirmed by single-crystal X-ray diffraction. An anion exchange experiment proved that complex 2 could transform into complex 1 in solution. The two complexes exhibited a highly catalytic performance in acceptorless 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 yields were still obtained by prolonging the reaction time. Especially, this system successfully realized the dehydrogenative cross-coupling to esters between two different primary alcohols.
Spontaneous formation of PMB esters using 4-methoxybenzyl-2,2,2- trichloroacetimidate
Shah, Jigisha P.,Russo, Christopher M.,Howard, Kyle T.,Chisholm, John D.
supporting information, p. 1740 - 1742 (2014/03/21)
Carboxylic acids are converted to the corresponding 4-methoxybenzyl (PMB) esters with 4-methoxybenzyl-2,2,2-trichloroacetimidate in the absence of an acid catalyst. This operationally simple procedure is a highly effective method for the formation of PMB esters. The reaction is promoted by the carboxylic acids themselves in excellent yields (72-99%). Sterically hindered carboxylic acids, which provide lower yields with other imidates, are esterified in higher yield with the more reactive PMB imidate. No racemization is observed in the case of carboxylic acids bearing an α-stereocenter, and no isomerization is observed with Z-α,β-unsaturated acids. This method may therefore find use in the esterification of complex or sensitive substrates where more common techniques lead to decomposition.
Covalently bound benzyl ligand promotes selective palladium-catalyzed oxidative esterification of aldehydes with alcohols
Liu, Chao,Tang, Shan,Zheng, Liwei,Liu, Dong,Zhang, Heng,Lei, Aiwen
supporting information; experimental part, p. 5662 - 5666 (2012/07/01)
It's a benzyl kind of magic: In the title reaction proceeding with benzyl chloride as the oxidant, the benzyl group serves as a carbon ligand, thus having an 3-coordination effect on palladium (see scheme). A variety of aldehydes and alcohols were selectively converted into the corresponding esters in good to excellent yields. Copyright
