2404-43-5Relevant articles and documents
An effective approach for the immobilization of chiral Mn(III) salen complexes through a supported ionic liquid phase
Lou, Lan-Lan,Yu, Kai,Ding, Fei,Zhou, Wei,Peng, Xiaojie,Liu, Shuangxi
, p. 6513 - 6516 (2006)
An effective method based on supported ionic liquid system was employed to immobilize chiral Mn(III) salen complexes. The prepared heterogeneous catalysts exhibited excellent activity and enantioselectivity in the asymmetric epoxidation of unfunctionalize
Epoxide Electroreduction
Huang, Cheng,Lu, Qingquan,Ma, Wan,Qi, Xiaotian,Xu, Minghao,Zheng, Xuelian
supporting information, p. 1389 - 1395 (2022/01/19)
Selective hydrogenation of epoxides would be a direct and powerful approach for alcohol synthesis, but it has proven to be elusive. Here, electrochemically epoxide hydrogenation using electrons and protons as reductants is reported. A wide range of primary, secondary, and tertiary alcohols can be achieved through selective Markovnikov or anti-Markovnikov ring opening in the absence of transition metals. Mechanistic investigations revealed that the regioselectivity is controlled by the thermodynamic stabilities of the in situ generated benzyl radicals for aryl-substituted epoxides and the kinetic tendency for Markovnikov selective ring opening for alkyl-substituted epoxides.
Construction of an Asymmetric Porphyrinic Zirconium Metal-Organic Framework through Ionic Postchiral Modification
Berijani, Kayhaneh,Morsali, Ali
, p. 206 - 218 (2021/01/11)
Herein, one kind of neutral chiral zirconium metal-organic framework (Zr-MOF) was reported from the porphyrinic MOF (PMOF) family with a metallolinker (MnIII-porphyrin) as the achiral polytopic linker [free base tetrakis(4-carboxyphenyl)porphyrin] and chiral anions. Achiral Zr-MOF was chiralized through the exchange of primitive anions with new chiral organic anions (postsynthetic exchange). This chiral functional porphyrinic MOF (CPMOF) was characterized by several techniques such as powder X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, 1H NMR, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller measurements. In the resulting structure, there are two active metal sites as Lewis acid centers (Zr and Mn) and chiral species as Br?nsted acid sites along with their cooperation as nucleophiles. This CPMOF shows considerable bimodal porosity with high surface area and stability. Additionally, its ability was investigated in asymmetric catalyses of prochiral substrates. Interactions between framework chiral species and prochiral substrates have large impacts on the catalytic ability and chirality induction. This chiral catalyst proceeded asymmetric epoxidation and CO2 fixation reactions at lower pressure with high enantioselectivity due to Lewis acids and chiral auxiliary nucleophiles without significant loss of activity up to the sixth step of consecutive cycles of reusability. Observations revealed that chiralization of Zr-MOF could happen by a succinct strategy that can be a convenient method to design chiral MOFs.
Immobilization of (tartrate-salen)Mn(III) polymer complexes into SBA-15 for catalytic asymmetric epoxidation of alkenes
Jia, Yihong,ALOthman, Zeid A.,Liang, Rui,Cha, Shuangshuang,Li, Xiaoyong,Ouyang, Weiyi,Zheng, Aqun,Osman, Sameh M.,Luque, Rafael,Sun, Yang
, (2020/08/19)
A series of (tartrate-salen)Mn(III) polymer complexes were prepared and immobilized into SBA-15, being subsequently employed as catalysts in the asymmetric epoxidation of alkenes. 1H NMR, FT-IR, UV–vis, elemental analysis, GPC and ICP-AES demonstrated the successful synthesis of polymer complexes, while powdered XRD, nitrogen physisorption and XPS studies proved the immobilization of polymer complexes into SBA-15. Both homogeneous and heterogeneous catalysis revealed that configurations of major epoxide products were still determined by salen chirality but e.e. values could be improved when tartrate and salen were configurationally identical. Combinations of (R,R)-salen with (R,R)-tartrate usually offered higher enantioselectivities. SBA-15 was satisfactory supporting material due to the high enantioselectivities and recycling yields obtained. The synthesized SBA-15-supported (tartrate-salen)Mn(III) catalysts showed continuous high enantioselectivities for epoxidation of α-methylstyrene, indicating great prospects for large-scale production.