32462-30-9Relevant articles and documents
Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
supporting information, p. 390 - 398 (2021/01/13)
Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
Optical resolution and mechanism using enantioselective cellulose, sodium alginate and hydroxypropyl-β-cyclodextrin membranes
Yuan, Li-Ming,Ma, Wei,Xu, Mei,Zhao, Hui-Lin,Li, Yuan-Yuan,Wang, Rui-Lin,Duan, Ai-Hong,Ai, Ping,Chen, Xue-Xian
, p. 315 - 324 (2017/05/29)
Chiral solid membranes of cellulose, sodium alginate, and hydroxypropyl-β-cyclodextrin were prepared for chiral dialysis separations. After optimizing the membrane material concentrations, the membrane preparation conditions and the feed concentrations, enantiomeric excesses of 89.1%, 42.6%, and 59.1% were obtained for mandelic acid on the cellulose membrane, p-hydroxy phenylglycine on the sodium alginate membrane, and p-hydroxy phenylglycine on the hydroxypropyl-β-cyclodextrin membrane, respectively. To study the optical resolution mechanism, chiral discrimination by membrane adsorption, solid phase extraction, membrane chromatography, high-pressure liquid chromatography ultrafiltration were performed. All of the experimental results showed that the first adsorbed enantiomer was not the enantiomer that first permeated the membrane. The crystal structures of mandelic acid and p-hydroxy phenylglycine are the racematic compounds. We suggest that the chiral separation mechanism of the solid membrane is “adsorption – association – diffusion,” which is able to explain the optical resolution of the enantioselective membrane. This is also the first report in which solid membranes of sodium alginate and hydroxypropyl-β-cyclodextrin were used in the chiral separation of p-hydroxy phenylglycine.
One-pot, regioselective synthesis of substituted arylglycines for kinetic resolution by penicillin G acylase
Grundmann, Peter,Fessner, Wolf-Dieter
experimental part, p. 1729 - 1735 (2009/07/24)
Amido-alkylation of electron-rich arenes with phenylacetamide and glyoxylic acid offers an in-expensive route to a large variety of N-phenylacetylated arylglycines that are suited for immediate enzymatic resolution by penicillin G acylase. When performed under mild conditions at 5 °C in acetic acid/HCl, this simple one-pot operation resulted in the formation of single regioisomers only (≥98%). Subsequent kinetic resolution of the amino acid derivatives by penicillin G acylase at pH 8.0 occurred generally with E values >100 and thus furnished free (S)-configurated arylglycines with high enantiomeric purity. The corresponding enantiopure (R)-substrates, easily separable by a phase-selective extraction process, provided the corresponding (R)-enantiomers upon conventional hydrolysis. This one-pot, two-step procedure for arylglycine synthesis, resolution and work-up requires a minimum of equipment and grants rapid access to both enantiopure (S)- and (R)-antipodes of non-natural α-amino acids in small-to large-scale quantities.
