536-75-4Relevant articles and documents
Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
supporting information, p. 2157 - 2161 (2021/05/21)
The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
Scalable, Telescoped Hydrogenolysis-Enzymatic Decarboxylation Process for the Asymmetric Synthesis of (R)-α-Heteroaryl Propionic Acids
Blakemore, Caroline A.,France, Scott P.,Samp, Lacey,Nason, Deane M.,Yang, Eddie,Howard, Roger M.,Coffman, Karen J.,Yang, Qingyi,Smith, Aaron C.,Evrard, Edelweiss,Li, Wei,Dai, Linlin,Yang, Lixia,Chen, Zhiguang,Zhang, Qingli,He, Fangyan,Zhang, Jiesen
supporting information, p. 421 - 426 (2020/11/12)
Enantiopure α-aryl propionic acids are useful building blocks for pharmaceutical research and can be accessed enzymatically using arylmalonate decarboxylases (AMDases) from the corresponding malonic acids. However, the intrinsic instability of malonic acids is a major drawback to this approach in which spontaneous decarboxylation can occur, subsequently eroding enantioselectivity and giving rise to racemic products. This was particularly evident for a panel of N-heterocyclic propionic acids that we wished to access using the approach. Herein, we describe a process to overcome the spontaneous decarboxylation problem in which hydrogenolysis of the corresponding dibenzyl malonates was performed in a biphasic toluene-basic aqueous buffer mixture and telescoped into the subsequent AMDase step. This procedure enabled compounds to be accessed in high enantioselectivities and was successfully demonstrated on 120 g with high yield (76%) and ee (98%).
Rethinking Basic Concepts-Hydrogenation of Alkenes Catalyzed by Bench-Stable Alkyl Mn(I) Complexes
Weber, Stefan,St?ger, Berthold,Veiros, Luis F.,Kirchner, Karl
, p. 9715 - 9720 (2019/10/14)
An efficient additive-free manganese-catalyzed hydrogenation of alkenes to alkanes with molecular hydrogen is described. This reaction is atom economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. The most efficient precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid hydrogenolysis to form the active 16e Mn(I) hydride catalyst [Mn(dippe)(CO)2(H)]. A range of mono- A nd disubstituted alkenes were efficiently converted into alkanes in good to excellent yields. The hydrogenation of 1-alkenes and 1,1-disubstituted alkenes proceeds at 25 °C, while 1,2-disubstituted alkenes require a reaction temperature of 60 °C. In all cases, a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar were applied. A mechanism based on DFT calculations is presented, which is supported by preliminary experimental studies.
