5928-66-5Relevant articles and documents
Preparation of a novel bridged bis(β-cyclodextrin) chiral stationary phase by thiol-ene click chemistry for enhanced enantioseparation in HPLC
Gong, Bolin,Guo, Siyu,Zhang, Ning
, p. 35754 - 35764 (2021/12/02)
A bridged bis(β-cyclodextrin) ligand was firstly synthesized via a thiol-ene click chemistry reaction between allyl-ureido-β-cyclodextrin and 4-4′-thiobisthiophenol, which was then bonded onto a 5 μm spherical silica gel to obtain a novel bridged bis(β-cyclodextrin) chiral stationary phase (HTCDP). The structures of HTCDP and the bridged bis(β-cyclodextrin) ligand were characterized by the 1H nuclear magnetic resonance (1H NMR), solid state 13C nuclear magnetic resonance (13C NMR) spectra spectrum, scanning electron microscope, elemental analysis, mass spectrometry, infrared spectrometry and thermogravimetric analysis. The performance of HTCDP in enantioseparation was systematically examined by separating 21 chiral compounds, including 8 flavanones, 8 triazole pesticides and 5 other common chiral drugs (benzoin, praziquantel, 1-1′-bi-2-naphthol, Tr?ger's base and bicalutamide) in the reversed-phase chromatographic mode. By optimizing the chromatographic conditions such as formic acid content, mobile phase composition, pH values and column temperature, 19 analytes were completely separated with high resolution (1.50-4.48), in which the enantiomeric resolution of silymarin, 4-hydroxyflavanone, 2-hydroxyflavanone and flavanone were up to 4.34, 4.48, 3.89 and 3.06 within 35 min, respectively. Compared to the native β-CD chiral stationary phase (CDCSP), HTCDP had superior enantiomer separation and chiral recognition abilities. For example, HTCDP completely separated 5 other common chiral drugs, 2 flavanones and 3 triazole pesticides that CDCSP failed to separate. Unlike CDCSP, which has a small cavity (0.65 nm), the two cavities in HTCDP joined by the aryl connector could synergistically accommodate relatively bulky chiral analytes. Thus, HTCDP may have a broader prospect in enantiomeric separation, analysis and detection. This journal is
Enantioselective N-heterocyclic carbene-catalysed intermolecular crossed benzoin condensations: Improved catalyst design and the role of in situ racemisation
Delany, Eoghan G.,Connon, Stephen J.
supporting information, p. 248 - 258 (2021/01/14)
The enantioselective intermolecular crossed-benzoin condensation mediated by novel chiral N-heterocyclic carbenes derived from pyroglutamic acid has been investigated. A small library of chiral triazolium ions were synthesised. Each possessed a tertiary alcohol H-bond donor and a variable N-aryl substituent. It was found that increasing both the steric requirement and the electron-withdrawing characteristics of the N-aryl ring led to more chemoselective, efficient and enantioselective chemistry, however both quenching the reaction at different times and deuterium incorporation experiments involving the product revealed that this is complicated by product racemisation in situ (except in the case of benzoin itself), which explains the dependence of enantioselectivity on the electrophilicity of the reacting aldehydes common in the literature. Subsequent protocol optimisation, where one reacting partner was an o-substituted benzaldehyde, allowed a range of crossed-benzoins to be synthesised in moderate-good yields with moderate to excellent enantioselectivity.
Spectroscopic evidence of chirality in tetranuclear Cu(II)-Schiff base complexes, catalytic potential for oxidative kinetic resolution of racemic benzoin
Sadhukhan, Dipali,Ghosh, Prithwi,Ghanta, Susanta
, p. 1714 - 1724 (2020/12/17)
Two chiral Schiff base ligands 2-((1-hydroxy-3-phenylpropan-2-ylimino)methyl)-6-methoxyphenol (L1H2) and 2-(4-hydroxy-3-isopropylbut-1-enyl)-6-methoxyphenol (L2H2) have been synthesized by the condensation of l-phenylalaninol/l-valinol and o-vanillin (2-hydroxy-3-methoxy benzaldehyde). A tetranuclear homometallic Cu(II) complex [Cu4(L1H)2(L1)2] (ClO4)2 (C1) and a hexanuclear heterometallic complex [Cu4(L2)4Na2(DMF)2(H2O)] (ClO4)2 (C2) have been synthesized with the ligands. Both the complexes possess cubane like Cu4O4 core with interesting structural variations and inherit the chirality of their corresponding ligands. The catalytic potential of the complexes has been explored for the oxidative kinetic resolution of racemic benzoin. The electronic, optical and chiroptical properties of the ligands and the complexes have been studied by DFT and TD-DFT calculations.
