849412-56-2Relevant 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.
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.
Lanthanide complexes combined with chiral salen ligands: Application in the enantioselective epoxidation reaction of α,β-unsaturated ketones
Xia, Xuexiu,Lu, Chengrong,Zhao, Bei,Yao, Yingming
, p. 13749 - 13756 (2019/05/16)
Readily available lanthanide amides Ln[N(SiMe3)2]3 (Ln = Nd (1), Sm (2), Eu (3), Yb (4), La (5)), combined with chiral salen ligands H2La ((S,S)-N,N′-di-(3,5-disubstituted-salicylidene)-1,2-cyclohexan
Kinetic resolution of 2,3-epoxy 3-aryl ketones via catalytic asymmetric ring-opening with pyrazole derivatives
Huang, Tianyu,Lin, Lili,Hu, Xiaolei,Zheng, Jianfeng,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 11374 - 11377 (2015/08/18)
A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide-Sc(III) complex as the catalyst. A wide variety of substrates were readily scoped, and the selectivity factors obtained were excellent (up to >300).
Manganese catalysts with C1-symmetric N4 ligand for enantioselective epoxidation of olefins
Wang, Bin,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
supporting information; experimental part, p. 6750 - 6753 (2012/07/03)
Bioinspired manganese complexes based on N4 ligands, with a more rigid, chiral diamine derived from proline and two benzimidazoles, were synthesized and applied to epoxidize olefins with hydrogen peroxide as a clean oxidant. Notably, 60-99 % isolated yields and excellent ee values (up to 95 %) were obtained by using low catalyst loadings (0.01-0.2 mol %; see scheme; F green, S yellow). Copyright
Asymmetric epoxidation of substituted chalcones and chalcone analogues catalyzed by α-d-glucose- and α-d-mannose-based crown ethers
Mako, Attila,Rapi, Zsolt,Keglevich, Gyoergy,Szoellsy, Aron,Drahos, Laszlo,Hegeds, Laszlo,Bako, Peter
experimental part, p. 919 - 925 (2010/08/06)
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfer catalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetric induction. It was found that the position of the substituents in the aromatic ring of the chalcone had an influence both on the chemical yields and enantiomeric excesses. The lowest enantioselectivities (62-83% ee) were found in the case of ortho-substituted model compounds. The highest ee values (ee of 83-97%) were obtained in the case of para-substituted models. From among the chalcone analogues, the maximum ee (90-92%) was detected for the model compound having α-tert-butyl- and β-aryl groups. Using glucose-based crown ether 1, formation of the (-)-enantiomer was preferred, while applying mannose-based 2 as the catalyst, the (+)-enantiomer was in excess.
