A rare case of facial selectivity inversion for Sharpless asymmetric dihydroxylation in a series of structurally homogeneous substrates: synthesis of non-racemic 3-(nitrophenoxy)-propane-1,2-diols
摘要:
Asymmetric dihydroxylation of mono nitrophenyl allyl ethers leads to the corresponding non-racemic 3-(nitrophenoxy)-propane-1,2-diols 1a-c. As this takes place, regardless of the reagent used (AD-mix-alpha or AD-mix-beta), the configuration of the predominant enantiomer for the para- and meta-nitrosubstituted products is opposite to the configuration of the ortho-nitrophenyl derivative. A correlation between the melting points and vibrational spectra of the racemic and enantiopure diols 1a-c allowed us to establish that all of the chiral substances investigated formed stable racemic compounds in the solid phase. (C) 2014 Elsevier Ltd. All rights reserved.
ortho‐substituted phenyl glycidyl ethers and para‐nitrostyrene oxide. Worthy of note is that the substrate structure remarkably affected the enantioselectivities of the enzyme, as a reversed (S)‐enantiopreference was unexpectedly observed for the ortho‐nitrophenyl glycidyl ether. As a proof‐of‐concept, five enantiopure epoxides (>99% ee) were obtained in high yields, and a gram‐scale preparation of
Chiral Nanoporous Metal–Metallosalen Frameworks for Hydrolytic Kinetic Resolution of Epoxides
作者:Chengfeng Zhu、Guozan Yuan、Xu Chen、Zhiwei Yang、Yong Cui
DOI:10.1021/ja302340b
日期:2012.5.16
recyclable heterogeneous catalyst for hydrolytickineticresolution (HKR) of racemic epoxides with up to 99.5% ee. The MOF structure brings Co(salen) units into a highly dense arrangement and close proximity that enhances bimetallic cooperative interactions, leading to improved catalytic activity and enantioselectivity in HKR compared with its homogeneous analogues, especially at low catalyst/substrate ratios
The phenyl glycidyl ether derivatives have been kinetically resolved with the growing cells of Bacillus alcalophilus MTCC10234 yielding (S)-epoxides with up to >99% ee and (R)-diols with up to 89% ee. The enantiomeric ratio (E) of up to 67 has been obtained for biohydrolysis process. The effect of different substituents of phenyl glycidyl ether on the biocatalytic efficiency of B. alcalophilus MTCC10234