189161-37-3Relevant academic research and scientific papers
Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 2778 - 2782 (2021/04/29)
Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
Enantioselective Epoxidation of Electron-Deficient Alkenes Catalyzed by Manganese Complexes with Chiral N4 Ligands Derived from Rigid Chiral Diamines
Chen, Xiangning,Gao, Bao,Su, Yijin,Huang, Hanmin
supporting information, p. 2535 - 2541 (2017/08/16)
A series of tetradentate sp2N/sp3N hybrid chiral N4 ligands derived from rigid chiral diamines were synthesized, which enabled the first manganese-catalyzed enantioselective epoxidation of electron-deficient alkenes with hydrogen peroxide (H2O2) as an oxidant. The reaction furnishes enantiomerically pure epoxy amides, epoxy ketones as well as epoxy esters in good yields and excellent enantioselectivities (up to 99.9% ee) with lower catalyst loading. Preliminary studies on structure–activity relationship demonstrated that maintaining comparatively lower electron-donating ability of the sp3N and relatively higher electron-donating ability of sp2N of the N4 ligands is beneficial to getting higher activity and selectivity, thus providing us a new view to understand epoxidation with H2O2. (Figure presented.).
Highly efficient asymmetric epoxidation of electron-deficient α,β-enones and related applications to organic synthesis
Zheng, Changwu,Li, Yawen,Yang, Yingquan,Wang, Haifeng,Cui, Haifeng,Zhang, Junkang,Zhao, Gang
supporting information; experimental part, p. 1685 - 1691 (2011/02/25)
The asymmetric epoxidation of electrondeficient olefins has been achieved using inexpensive and readily available prolinols as catalysts with good to excellent yields and enantioselectivities. The utility of the resulting chiral epoxides was illustrated b
Nitrile biotransformations for highly efficient and enantioselective syntheses of electrophilic oxiranecarboxamides
Wang, Mei-Xiang,Lin, Shuang-Jun,Liu, Chu-Sheng,Zheng, Qi-Yu,Li, Ji-Sheng
, p. 4570 - 4573 (2007/10/03)
Catalyzed by a nitrile hydratase/amidase-containing microbial Rhodococcus sp. AJ270 whole-cell catalyst, a number of racemic trans-2,3-epoxy-3-arylpropanenitriles 1 underwent rapid and efficient hydrolysis under very mild conditions to afford 2R,3S-2-arylglycidamides 2 in excellent yield with enantiomeric excess higher than 99.5%. The overall enantioselectivity of the biotransformations originated from the combined effects of a dominantly high 2S-enantioselective amidase and low 2S-enantioselective nitrile hydratase involved in the cell. The influence of the substrates on both reaction efficiency and enantioselectivity was also discussed in terms of steric and electronic effects.
