801288-07-3Relevant academic research and scientific papers
Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth-Metal Complexes Supported with Phenoxy-Functionalized TsDPEN Ligands
Yu, Qishun,Lu, Chengrong,Zhao, Bei
supporting information, p. 2529 - 2537 (2021/07/28)
Six novel chiral rare-earth-metal complexes bearing the phenoxy-functionalized TsDPEN ligand H3L1 (H3L1 = N-((1R,2R)-2-((3,5-di-Tert-butyl-2-hydroxybenzyl)amino)-1,2-diphenylethyl)-4-methylbenzenesulfonamide) were synthesized successfully and well characterized. The solid-state structures of four tetranuclear rare-earth-metal complexes [RE2L13]2 (RE = Nd (1), Sm (2), Eu (3), Gd (4)) and the dual-core yttrium complex Y2L13 (5) were determined by X-ray diffraction, respectively. The structure of lanthanum complex 6 was speculated by the 1H DOSY spectroscopy in THF-d8 together with DFT calculations. Complexes 1-5 were employed to catalyze the enantioselective hydroboration of ketones and α,β-unsaturated ketones using pinacolborane (HBpin) as a reductant, and complex 1 gave better outcomes in comparison to the others. The corresponding secondary alcohols were obtained in excellent yields and moderate ee values. The same results were also achieved using the combined catalyst system of the neodymium amide Nd[N(SiMe3)2]3 with the phenoxy-functionalized TsDPEN ligand H3L1 in a 1:1.5 molar ratio.
Mechanism-Inspired Design of Bifunctional Catalysts for the Alternating Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides
Abel, Brooks A.,Lidston, Claire A. L.,Coates, Geoffrey W.
, p. 12760 - 12769 (2019/08/26)
Advances in catalysis have enabled the ring-opening copolymerization of epoxides and cyclic anhydrides to afford structurally and functionally diverse polyesters with controlled molecular weights and dispersities. However, the most common systems employ b
Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones Catalyzed by Rare-Earth Amides [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 with Phenoxy-Functionalized Chiral Prolinols
Zeng, Chao,Yuan, Dan,Zhao, Bei,Yao, Yingming
, p. 2242 - 2245 (2015/05/13)
A simple and efficient catalytic enantioselective epoxidation of α,β-unsaturated ketones has been successfully developed, which was catalyzed by rare-earth metal amides [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 (RE = Yb (1), La (2), Sm (3), Y (4), Lu (5)) in the presence of phenoxy-functionalized chiral prolinols at room temperature using tert-butylhydroperoxide (TBHP) as the oxidant. The combination of an Yb-based amide 1 and a chiral proligand (S)-2,4-di-tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol) performed very well, and both the yields and the enantiomeric excess of the chiral epoxides reached up to 99% and 99% ee. (Figure Presented).
Large ultra-high molecular weight polyethylene spherical particles produced by AlR3 activated half-sandwich chromium(iii) catalysts
Sun, Mingtai,Xu, Tieqi,Gao, Wei,Liu, Yang,Wu, Qiaolin,Mu, Ying,Ye, Ling
experimental part, p. 10184 - 10194 (2011/12/05)
A series of half-sandwich pentamethylcyclopentadienyl chromium(iii) complexes bearing a salicylaldiminato ligand, Cp*[2-R1-4-R 2-6-(CHNR3)C6H2O]CrCl [R1 = iPr (1, 4), tBu (2, 3, 5), Ad (6); R2 = H (1, 2, 3), tBu (4, 5, 6); R3 = iPr (1, 2, 5, 6), tBu (3, 4)], were synthesized. All complexes were characterized by elemental analyses and the structures of complexes 1-4 and 6 were determined by X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlR3, complexes 1-6 all catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with a diameter of 1-6 mm. The catalytic activity of these complexes and the molecular weight of the produced polyethylene can be tuned in a broad range by changing the R1, R 2, and R3 groups as well as the AlR3 cocatalyst. It was found that complex 6 with R1 = Ad, R2 = tBu, and R3 = iPr shows the highest catalytic activity and produces polyethylene with the highest molecular weight. The Royal Society of Chemistry 2011.
Co-metal-free enantioselective conjugate addition reactions of zinc reagents
Ay, Sefer,Nieger, Martin,Braese, Stefan
experimental part, p. 11539 - 11556 (2009/12/07)
Asymmetric conjugate addition of diethylzinc to cinnamaldehyde in a co-metal-free fashion by using N,O-ligands with planar and central chirality is described. Different modulations of the ligand structure, including several combinations of the chiral units, indicate that a [2.2]paracyclophane backbone is essential for the activity and the enantioselectivity of the generated active catalyst. By using the optimized ligand, an isolated yield of 90 % was obtained with up to 99 % ee.
