189017-49-0Relevant academic research and scientific papers
Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by rare-earth metal amides RE[N(SiMe3)2]3with chiral TADDOL ligands
Shan, Haiwen,Lu, Chengrong,Zhao, Bei,Yao, Yingming
, p. 1043 - 1053 (2021/01/25)
The catalytic asymmetric epoxidation of α,β-unsaturated ketones by tert-butylhydroperoxide (TBHP) has been well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Y(4), Yb(5)) with chiral TADDOL ligands. It was found that
Asymmetric epoxidation of α,β-unsaturated ketones via an amine-thiourea dual activation catalysis
Zhang, Lu-Wen,Wang, Li,Ji, Nan,Dai, Si-Yang,He, Wei
supporting information, (2021/03/15)
A simple asymmetric epoxidation method is developed to effectively synthesize chiral α-carbonyl epoxides through an amine-thiourea dual activation catalysis. In this method, TBHP, as an oxidant, determined the reaction rate, and the chiral amine-thiourea catalyst effectively controlled the stereoselectivity of the reaction, and KOH promoted deprotonation. 22 examples of α,β-unsaturated ketones with various substituent groups are smoothly converted into α-carbonyl epoxides with moderate to excellent enantiomeric excess.
Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones Using Amide-Based Cinchona Alkaloids as Hybrid Phase-Transfer Catalysts
Jurczak, Janusz,Majdecki, Maciej,Tyszka-Gumkowska, Agata
, (2020/11/13)
A series of 20 one chiral epoxides were obtained with excellent yields (up to 99%) and enantioselectivities (up to >99% ee) using hybrid amide-based Cinchona alkaloids. Our method is characterized by low catalyst loading (0.5 mol %) and short reaction times. Moreover, the epoxidation process can be carried out in 10 cycles, without further catalyst addition to the reaction mixture. This methodology significantly enhance the scale of the process using very low catalyst loading.
The Synthesis of Hydrobenzoin-Based Monoaza Crown Ethers and Their Application as Recyclable Enantioselective Catalysts
Nemcsok, Tamás,Rapi, Zsolt,Bagi, Péter,Oláh, Attila,Keglevich, Gy?rgy,Bakó, Péter
, p. 930 - 938 (2019/11/22)
Abstract: New recyclable monoaza-15-crown ethers have been synthesized starting from (R,R)-(+)- and (S,S)-(?)-hydrobenzoin. These macrocycles proved to be efficient and reusable phase transfer catalysts in a few asymmetric reactions under mild conditions.
Organocatalytic Enantioselective γ-Elimination: Applications in the Preparation of Chiral Peroxides and Epoxides
Chen, Zhili,Gong, Xiangnan,Hu, Fangli,Huang, Shengli,Jia, Shiqi,Qin, Wenling,Tan, Yu,Xu, Da,Yan, Hailong
, p. 1934 - 1940 (2020/03/24)
An organocatalyzed enantioselective γ-elimination process has been achieved and applied in the kinetic resolution of peroxides to access chiral peroxides and epoxides. The reaction provided a pathway for the preparation of two useful synthetic and biologically important structural motifs through a single-step reaction. A range of substrates has been resolved with a selectivity factor up to 63. The obtained enantioenriched peroxides and epoxides allowed a series of transformations with retained optical purities.
Chiral calcium-catalyzed asymmetric epoxidation reactions using hydrogen peroxide as the terminal oxidant
Yamashita, Yasuhiro,Macor, Joseph Alexander,Fushimi, Seiya,Tsubogo, Tetsu,Kobayashi, Shū
, p. 847 - 850 (2018/09/10)
Asymmetric epoxidation reactions of chalcone derivatives catalyzed by chiral calcium complexes using hydrogen peroxide were developed. The epoxidation reactions proceeded smoothly to afford the desired products in good yields with good enantioselectivitie
Syntheses, Structures, and Catalytic Activities of the Anionic Heterobimetallic Rare-Earth Metal Complexes Supported by Pyrrolyl-Substituted 1,2-Diimino Ligands
Wang, Wei,Wang, Xiaojia,Zhou, Shuangliu,Xu, Xiaolong,Du, Jun,Zhang, Lijun,Mu, Xiaolong,Wei, Yun,Zhu, Xiancui,Wang, Shaowu
supporting information, p. 10390 - 10400 (2018/08/28)
A series of the anionic heterobimetallic rare-earth metal complexes supported by trans- or chiral pyrrolyl-substituted 1,2-diimino ligands were synthesized in good yields via reactions of [(Me3Si)2N]3RE(μ-Cl)Li(THF)3
Asymmetric Epoxidation of Olefins with H2O2 Catalyzed by a Bioinspired Aminopyridine N4 Iron Complex
Wang, Wenfang,Sun, Qiangsheng,Xu, Daqian,Xia, Chungu,Sun, Wei
, p. 420 - 424 (2017/02/15)
An iron complex with a chiral aminopyridine N4 ligand bearing strong electron-donating and bulky morpholine groups on the ligand is synthesized and characterized. The iron complex serves to efficiently catalyze the asymmetric epoxidation of various olefins by employing aqueous hydrogen peroxide as the green oxidant, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 93 % yield and 99.9 % ee). Owing to the introduction of morpholine functional groups on the ligand, the Fe-catalyzed reaction can proceed with a catalytic amount of the carboxylic acid partner (3 mol %).
Highly selective multifunctional nanohybrid catalysts for the one-pot synthesis of α,β-epoxy-chalcones
Crivoi, Dana-Georgiana,Segarra, Anna M.,Medina, Francesc
, p. 120 - 128 (2016/01/09)
An efficient one-pot heterogeneous process for producing chiral α,β-epoxy-chalcones from the corresponding aldehydes and ketones has been described. The nanohybrid materials based on poly-l-leucine immobilised into rehydrated hydrotalcites did not require any pre-activation and were easily recovered and recycled for four consecutive runs without losing their catalytic efficiency in terms of conversion, total selectivity towards the corresponding epoxy-chalcones and excellent enantioselectivity.
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
supporting information, 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).
