Cellulose derivative chiral stationary phase based on pi-hole bond and preparation and application thereof

Abstract

The invention provides a pai-hole bond-based cellulose derivative chiral stationary phase as well as preparation and application thereof. The structural formula of the cellulose derivative is shown in the specification. According to the invention, a side group with pi-hole bond donor characteristics is introduced into the molecular structure of the CSPs, so that the recognition and separation capabilities of important electron-rich chiral compounds such as non-polar terpenes, non-polar aromatic hydrocarbons, complex-structure Lewis alkali drugs and the like which are difficult to be chirally recognized and separated under general conditions are improved, the resolution range is widened, and the preparation of novel CSPs is guided. The prepared CSPs containing the pi-hole bond donor can form relatively strong pi-hole... pi electron interaction with relatively abundant pi electrons of electron-rich chiral substrates such as terpene and the like, and under the assistance of interaction such as space matching effect and air resistance of a cellulose side group chiral cavity, the CSPs can be used for preparing the chiral cellulose. Efficient chiral recognition and separation of non-polar / weak-polar electron-rich compounds can be realized, and help is provided for development and optical purity detection of non-polar / weak-polar electron-rich chiral drugs. Wherein # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of HPLC chiral stationary phase material development and chiral recognition and separation technology, and specifically relates to a cellulose derivative chiral stationary phase with a strong π-hole bond donor side group, its preparation, and its application in the recognition and separation of electron-rich chiral compounds. Background Art

[0002] High-performance liquid chromatography (HPLC) equipped with chiral columns is currently the most common method for determining the optical purity of chiral compounds and is also widely used for the preparation of small quantities of optically pure enantiomers. Despite this, chiral HPLC is still unable to effectively separate non-polar / weakly polar terpenes such as zingiberene, which exhibit antioxidant, anti-inflammatory, and anti-tumor activities, and electron-rich chiral aromatic compounds such as 2-methylcyclopropylbenzene, which are important pharmaceutical intermediates. This is primarily due to their weak interactions with HPLC chiral stationary phases (CSPs), making it difficult to form stable substrate / CSP complexes.

[0003] The optical purity of non-polar / weakly polar chiral compounds is currently mainly characterized by specific rotation, 2D NOESY nuclear magnetic resonance, and gas chromatography (GC). However, since their optical activity is usually weak, the reliability of the results obtained by specific rotation is low. The 2D NOESY method requires the addition of chiral auxiliary agents, and has difficulty in signal differentiation, low sensitivity, complex experiments, and is easily affected by molecular size and dynamic behavior. The chiral GC method has problems such as a narrow substrate applicability and complex sample processing. The lack of simple and efficient characterization methods for the optical purity of non-polar / weakly polar chiral compounds has greatly affected the development of non-polar terpenes and other drugs.

[0004] A π-hole refers to a region of positive electrostatic potential perpendicular to the molecular framework, formed by the asymmetric charge distribution of the π-electron cloud in molecules containing electron-withdrawing groups (such as polyfluorinated aromatic compounds). The application of π-hole bonds in supramolecular self-assembly, adsorption separation, and organic optoelectronics has been widely reported. Zhang Jialing et al. synthesized a perfluorobenzene-bonded silica gel adsorbent that forms π-hole·π-electron interactions with polycyclic aromatic hydrocarbons (PAHs). This adsorbent was used for the solid-phase extraction of 16 PAHs from water, demonstrating high adsorption capacity for PAHs with 4–6 benzene rings, with a recovery rate approximately 20% higher than that of conventional octadecyl silica gel adsorbents. Peluso et al. investigated the separation ability of 5,5′-dibromo-2,2′-dichloro-3-seleno-4,4′-bipyridine, which interacts with cellulose aromatic derivative CSPs through both chalcogen bonds (ChB, a σ-hole bond) and π-hole bonds, on a polysaccharide chiral column. They found that the strongly electron-withdrawing pentafluorophenyl group enhanced the depth of the σ-hole above the selenium atom, increasing its positive potential. Furthermore, the π-hole perpendicular to the pentafluorophenyl group was also positively charged, allowing the chiral substrate molecule to act as both a σ-hole and a π-hole bond donor, enhancing the chiral recognition ability with the CSPs and significantly improving the chiral separation performance compared to the control group. However, no one has yet used the π-hole bond as the primary interaction donor in the design of CSPs.

[0005] Among the various CSPs reported so far, polysaccharide derivatives are the most widely used CSP packing materials for commercial chiral columns. They exhibit excellent chiral separation capabilities, a wide resolution range, and strong stability, with excellent recognition and separation capabilities for a wide range of chiral compounds, including amines, alcohols, phenols, ketones, aromatic compounds, carboxylic acids, and esters. This is primarily due to the ordered, optically active helical backbone of polysaccharide derivatives and the chiral cavity formed by the side groups arranged around the backbone, which allows for spatial matching with a variety of chiral substrates with different topological structures. This is supplemented by hydrogen bonding, π-π, dipole-dipole, and hydrophobic interactions between substituents such as side-group-derivatized aromatic rings and chiral substrates, resulting in excellent chiral recognition and separation performance. Unfortunately, these CSPs lack suitable interactions with non-polar chiral substrates such as terpenes, preventing them from forming stable complexes, making chiral recognition and separation of these substrates difficult. Summary of the Invention

[0006] The purpose of the present invention is to solve the technical problem that electron-rich chiral compounds such as non-polar / weakly polar terpenes, non-polar electron-rich aromatic hydrocarbons, and complex structure Lewis base drugs are difficult to chirally recognize and separate, and to provide a cellulose derivative CSPs with strong π-hole bond donor side groups and a preparation method thereof, as well as a technology for chiral recognition and separation of weakly polar / non-polar electron-rich chiral compounds based on the CSPs.

[0007] π-hole bonds form through electrostatic interactions between the positively charged π-hole and the negatively charged regions of electron-rich substrates, involving π-hole···π-electron / anion / lone-pair interactions. Compared to the strongly directional nature of hydrogen bonds, π-hole bonds offer multiple directions of action and high spatial flexibility, easily adapting to the stereostructures of diverse electron-rich chiral molecules. This makes it possible to identify and separate electron-rich chiral substrates such as non-polar terpenes and aromatic hydrocarbons, as well as some complex Lewis base drugs that are difficult to separate using commercial columns such as AD-H and OD-H due to poor steric matching.

[0008] One of the objects of the present invention is to provide a cellulose derivative having a strong π-hole bond donor side group (hereinafter referred to as cellulose derivative).

[0009] The cellulose derivative with a strong π-hole bond donor side group provided by the present invention is prepared by an addition reaction between pentafluorophenyl isocyanate and cellulose hydroxyl groups, wherein the side group substitution degree is 2-3;

[0010] The cellulose derivative having a strong π-hole bond donor side group has a structural formula as shown below:

[0011]

[0012] in,

[0013] The cellulose derivative having a strong π-hole bond donor side group is prepared by any one of the following methods 1 to 3.

[0014] Among them, method 1 includes the following steps:

[0015] (1) Cellulose is dissolved in DMAc / LiCl at a certain temperature, cooled to room temperature, and an excess of pentafluorophenyl isocyanate is added dropwise. The addition reaction of the two at room temperature is catalyzed by DMAP. After the reaction is complete, the product is precipitated with a precipitant, centrifuged, and then dissolved again in a good solvent. The product is dialyzed and precipitated again, centrifuged, and dried to obtain a preliminarily derivatized cellulose carbamate derivative.

[0016] (2) The preliminarily derivatized cellulose carbamate derivative obtained in step (1) is dissolved in DMAc, a catalyst dibutyltin dilaurate is added, and an excess of pentafluorophenyl isocyanate is added dropwise at 0°C, followed by heating to 40°C. After the reaction is completed, the product is precipitated with a precipitant, centrifuged, and then dissolved again with a good solvent, precipitated again, and centrifuged again. The above steps are repeated 3-4 times to completely remove impurities in the cellulose derivative. After drying, a highly substituted cellulose carbamate derivative cell-NPhF5, i.e., a cellulose derivative having a strong π-hole bond donor side group, can be obtained.

[0017] Method 2 includes the following steps:

[0018] Without performing step (2) of method 1, the reaction time of step (1) of method 1 is doubled to obtain;

[0019] Method 3 includes the following steps:

[0020] Cellulose is dissolved in DMAc / LiCl at 80°C and cooled to room temperature. The subsequent steps are the same as step (2) of method 1 (catalyst dibutyltin dilaurate is added, excess pentafluorophenyl isocyanate is added dropwise at 0°C, and then the temperature is raised to 40°C. After the reaction is completed, the product is precipitated with a precipitant, centrifuged and then dissolved again with a good solvent, precipitated again, and centrifuged again. The above steps are repeated 3-4 times to completely remove impurities in the cellulose derivative. After drying, a highly substituted cellulose carbamate derivative cell-NPhF5, i.e., a cellulose derivative with a strong π-hole bond donor side group, is obtained).

[0021] In step (1) of the above method, the certain temperature is 80-90°C;

[0022] The excess pentafluorophenyl isocyanate is 4.0-6.0 times the molar equivalent of cellulose;

[0023] The addition reaction time is 12-16h;

[0024] The precipitant is water / methanol = 1 / 1 (v / v) or water;

[0025] The good solvent is at least one of acetone, THF, and methanol;

[0026] The dialysate used in the dialysis is methanol.

[0027] In step (1) of the above method, the specific synthesis method of the preliminarily derivatized cellulose carbamate derivative can be carried out according to the existing literature (J. Chromatogr. A. 2018, 1572, 54.).

[0028] In step (2) of the above method, the amount of the catalyst dibutyltin dilaurate added is 0.1-1% of the mass of pentafluorophenyl isocyanate;

[0029] The excess pentafluorophenyl isocyanate is 3.0-5.0 times the molar equivalent of cellulose;

[0030] Reaction time is 10-16h;

[0031] The precipitant is at least one of methanol, n-hexane, and isopropanol, specifically n-hexane / isopropanol = 9 / 1 (v / v).

[0032] The good solvent is at least one of THF and acetone.

[0033] The theoretical value of the degree of substitution (DS) of the highly substituted cellulose carbamate derivative cell-NPhF5 is 3 (i.e., all three hydroxyl groups are substituted, and the actual value is between 2.5 and 3). 13 CNMR) characterization.

[0034] The application of the above-mentioned cellulose derivatives having strong π-hole bond donor side groups in the preparation of HPLC chiral stationary phase (CSPs) materials also falls within the protection scope of the present invention.

[0035] A second object of the present invention is to provide a HPLC chiral stationary phase (CSPs) material.

[0036] The HPLC chiral stationary phase (CSPs) material is prepared by coating the cellulose derivative having a strong π-hole bond donor side group onto the surface of amino-treated macroporous silica gel.

[0037] The above-mentioned HPLC chiral stationary phase (CSPs) material is prepared by a method comprising the following steps:

[0038] The cellulose derivative having a strong π-hole bond donor side group is dissolved in THF, and the resulting solution is added dropwise to the surface-aminated macroporous silica gel. After mixing, the solvent is removed to completely coat the cellulose derivative having a strong π-hole bond donor side group on the silica gel surface, thereby obtaining coated CSPs.

[0039] In the above method, in the THF solution of the cellulose derivative, the ratio of the cellulose derivative to THF may be 200 mg: 5-10 mL, specifically mL;

[0040] The mass ratio of the cellulose derivative to the surface amino-modified macroporous silica gel can be 200 mg:500-1000 mg, specifically 200 mg:800 mg;

[0041] The dropwise addition is carried out in multiple times. After each dropwise addition, the mixture is mixed by patting vigorously and then the solvent is removed by rotary evaporation. The patting time can be 4-7 minutes, specifically 5 minutes; the rotary evaporation time is also 4-7 minutes, specifically 5 minutes, and the last rotary evaporation time is 4 hours.

[0042] The above method further comprises the operation of packing the obtained coated CSPs into a chiral chromatography column.

[0043] Specifically, the operation includes: mixing the obtained HPLC chiral stationary phase (CSPs) material with a n-hexane / isopropanol mixture and liquid paraffin, ultrasonically promoting uniform dispersion of the system, flushing the chromatographic column with the solvent under a certain pressure, and then filling the CSPs material into the chromatographic column;

[0044] The added amount of the HPLC chiral stationary phase (CSPs) material, the n-hexane / isopropanol mixture (volume ratio of 90 / 10) and the liquid paraffin and the volume ratio of the chromatographic column can be: 1 g: 20-25 mL: 1 mL: inner diameter 0.21 cm x length 25 cm;

[0045] The pressure can specifically be 40 MPa;

[0046] The collection of 200 mL of effluent was used as the criterion for filling completion.

[0047] The use of the above-mentioned cellulose derivatives with strong π-hole bond donor side groups, the HPLC chiral stationary phase (CSPs) materials prepared therefrom, or the chiral chromatographic columns made from the HPLC chiral stationary phase (CSPs) materials in the efficient recognition and separation of electron-rich chiral substrates also falls within the scope of protection of the present invention.

[0048] The electron-rich chiral substrate is a non-polar / weakly polar electron-rich chiral substrate;

[0049] The electron-rich chiral substrate is selected from at least one of: 1) non-polar / weakly polar terpenes; 2) non-polar aromatic hydrocarbons; and 3) complex structure chiral Lewis bases.

[0050] Specifically, the electron-rich chiral substrate includes but is not limited to the following substances: Alkali, flavonoids, diphenylethylene oxide, binaphthol, trifluoro-1-9-anthracenethanol, β-gingerene, β-bisabolene, 2-methylcyclopropylbenzene, 1,1'-dimethylbinaphthyl, warfarin, amlodipine, azelnidipine, mirtazapine, nefopam, propranolol.

[0051] The present invention uses DMAP and dibutyltin dilaurate to catalyze the reaction of cellulose hydroxyl and isocyanate in steps, and constructs a cellulose carbamate derivative with high substitution degree and strong π-hole bond donor side group - pentafluorophenyl under mild conditions (reaction formula as shown in FIG). Figure 2 As shown in the figure, a tetrahydrofuran (THF) solution thereof was uniformly mixed with surface-amino-modified macroporous silica gel of different diameters (5 μm or 7 μm) to prepare coated CSPs, which were then packed into chiral chromatographic columns under high pressure. The electrostatic interaction between the positively charged π-hole bond donor pentafluorophenyl group and the negatively charged chiral electron-rich substrate was utilized to synergize hydrogen bonding, inclusion complexation, and spatial matching to achieve efficient recognition and separation of electron-rich chiral substrates.

[0052] The π-hole bond interaction adopted in the present invention is based on the principle that strongly electron-withdrawing polyfluorinated aromatic compounds form "π-holes" with positive electrostatic potential in the vertical direction of the molecule due to the asymmetric charge distribution of the π electron cloud. These "π-holes" can form π-hole bond interactions with the π electrons and lone pairs of electrons in electron-rich chiral compounds with negative electrostatic potential. The interaction force is close to or even exceeds that of hydrogen bonds (Phys. Chem. Chem. Phys. 2010, 12, 7748; Chem. Rev. 2022, 122, 13235; Chem. Rev. 2016, 116, 5072; ChemPhysChem 2015, 16, 2496.), which helps form highly stable transient diastereomeric complexes and achieves the analytical separation of electron-rich chiral substrates such as weak / non-polar terpenes, non-polar aromatic hydrocarbons, and complex Lewis bases that are difficult to separate using traditional HPLC.

[0053] The present invention also provides a chiral separation method for an electron-rich chiral substrate, wherein the electron-rich chiral substrate is a non-polar / weakly polar electron-rich chiral substrate selected from: 1) non-polar / weakly polar terpenes; 2) non-polar aromatic hydrocarbons; and 3) at least one of complex structure chiral Lewis bases.

[0054] Specifically, the electron-rich chiral substrate includes but is not limited to the following substances: Alkali, flavonoids, diphenylethylene oxide, binaphthol, trifluoro-1-9-anthracenethanol, β-gingerene, β-bisabolene, 2-methylcyclopropylbenzene, 1,1'-dimethylbinaphthyl, warfarin, amlodipine, azelnidipine, mirtazapine, nefopam, propranolol.

[0055] The chiral separation method of the electron-rich chiral substrate comprises the steps of preparing the electron-rich chiral substrate to be separated into a solution, injecting the solution into the chiral chromatographic column, eluting the solution, and performing HPLC separation.

[0056] The concentration of the solution may be 0.5-5 mg / mL.

[0057] The present invention has the following advantages:

[0058] 1. Structural design of CSPs based on π-hole bonds. Previous studies have shown that the interaction between chiral substrates with π-hole bond donors and CSPs with π-hole bond acceptor capabilities can enhance enantiomeric recognition and separation. However, the incorporation of π-hole bond donors into the design of CSPs has not yet been investigated. Introducing side groups with π-hole bond donor properties into the molecular structure of CSPs could enhance the recognition and separation capabilities of important electron-rich chiral compounds that are typically difficult to chirally recognize and separate, such as non-polar terpenes, non-polar aromatic hydrocarbons, and complex Lewis base drugs. This could broaden the resolution range and guide the preparation of novel CSPs.

[0059] 2. New CSPs capable of identifying and separating non-polar / weakly polar electron-rich chiral compounds such as terpenes. Non-polar / weakly polar electron-rich terpenes and other compounds generally struggle to achieve chiral recognition and separation due to a lack of intermolecular interactions with traditional CSPs. The CSPs containing π-hole bond donors prepared in this project can form strong π-hole···π-electron interactions with the relatively abundant π electrons of electron-rich chiral substrates such as terpenes. Assisted by the spatial matching and steric hindrance of the chiral cavities of the cellulose side groups, efficient chiral recognition and separation of non-polar / weakly polar electron-rich compounds can be achieved, aiding the development and optical purity testing of non-polar / weakly polar electron-rich chiral drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 Schematic diagram of the recognition and separation of electron-rich chiral compounds by cellulose derivatives CSPs based on π-hole bonds of the present invention.

[0061] Figure 2 The invention provides a synthetic route for the cellulose derivative having a strong π-hole bond donor side group.

[0062] Figure 3 The high temperature of the cellulose derivative cell-NPhF5 prepared in Example 1 of the present invention 1 H NMR spectrum (500 MHz, DMSO-d6 + 5% pentafluorochlorobenzene, 80°C).

[0063] Figure 4 Quantitative analysis of the inverse gating decoupling of the cellulose derivative cell-NPhF5 prepared in Example 1 of the present invention 13 CNMR spectrum (202 MHz, DMSO-d6, 40°C).

[0064] Figure 5 CD and UV-vis spectra of the cellulose derivative cell-NPhF5 prepared in Example 1 of the present invention (5.2×10 -4 M in THF).

[0065] Figure 6 The chemical structural formulas of the nine standard substrates involved in the present invention (the red ones are chirally separable substrates).

[0066] Figure 7 The chemical structural formula of the weakly polar / non-polar electron-rich chiral compound involved in the present invention (the red one is the chirally separable substrate).

[0067] Figure 8 The chemical structural formula of the complex chiral Lewis base drug involved in the present invention (the red one is the chirally separable substrate).

[0068] Figure 9 HPLC spectrum of the cellulose derivative cell-NPhF5 CSPs for the resolvable substrates among 9 standard substrates (n-hexane / isopropanol = 90 / 10 (v / v), 0.1 mL / min).

[0069] Figure 10 HPLC spectrum of the cellulose derivative cell-NPhF5 CSPs for the resolvable substrates among 9 standard substrates (n-hexane / isopropanol = 99 / 1 (v / v), 0.1 mL / min).

[0070] Figure 11 HPLC spectra of chiral separation of non-polar π-electron-rich substrates β-gingerene, β-bisabolene, 1,1'-dimethylbinaphthyl, and methylcyclopropylbenzene using cellulose derivative cell-NPhF5 CSPs (n-hexane / isopropanol = 99 / 1 (v / v), 0.1 mL / min).

[0071] Figure 12 HPLC chromatogram of chiral separation of Lewis base drugs warfarin, amlodipine, azelnidipine, mirtazapine, nefopam, and propranolol using cellulose derivative cell-NPhF5 CSPs (n-hexane / isopropanol = 90 / 10 (v / v), 0.1 mL / min) DETAILED DESCRIPTION

[0072] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0073] Unless otherwise noted, the experimental methods used in the following examples are all conventional methods and were performed according to the techniques or conditions described in literature in the field or according to product specifications. Unless otherwise noted, the materials and reagents used in the following examples were all commercially available. All purity levels were HPLC or high-purity EP grade. Unless otherwise noted, the experimental methods used in the following examples are all conventional experimental methods.

[0074] Cellulose was commercially available from Daicel Corporation, microcrystalline cellulose with a DP=200 value, CAS: 9004-34-6. Anhydrous lithium chloride was obtained from Sigma-Aldrich, CAS: 7447-41-8, and dried in a tube furnace at 500°C before use. Pentafluorophenyl isocyanate was purchased from Fluorochem, CAS: 1591-95-3. Anhydrous DMAc (CAS: 127-19-5), THF (CAS: 109-99-9), methanol (CAS: 67-56-4), DMAP (CAS: 1122-58-3), and dibutyltin dilaurate (CAS: 77-58-7) were all obtained from J&K. Acetone (CAS: 67-64-1) was obtained from Xilong Chemical Company. Macroporous silica gel (5 μm and 7 μm) was obtained from Suzhou Nano Micro. Surface amination was performed according to the reference method (J. Chromatogr. A 2018, 1572, 54) and dried under vacuum at 80°C for 12 h before use. All electron-rich racemic substrates were obtained from Sigma-Aldrich or J&K or synthesized according to existing literature methods.

[0075] Example 1. Preparation of cellulose pentafluorophenyl carbamate cell-NPhF5

[0076] Method 1: 0.20 g (1.23 mmol, 1.0 eq.) of microcrystalline cellulose (DP=200) was added to a 100 mL two-necked flask and dried under oil vacuum at 90°C for 3 h. The mixture was cooled to 80°C, evacuated, and replaced with nitrogen three times. 12 mL of anhydrous DMAc was added and stirred for 2 h until the mixture became slurry. The mixture was then cooled to room temperature and, under a nitrogen purge, 0.80 g (18.87 mmol) of dried anhydrous LiCl was quickly added. Once the reaction mixture was completely clear, a catalytic amount of DMAP was added, followed by the dropwise addition of 1.04 g of pentafluorophenyl isocyanate (4.92 mmol, 4.0 eq., relative repeating units). The mixture was stirred at room temperature for 16 h, then dropwise precipitated into a 1 / 1 (v / v) methanol / water mixture under vigorous stirring. The precipitate was separated by centrifugation. The precipitate was dissolved in 15 mL of methanol and placed in a dialysis bag with a molecular weight cutoff of 6000. The dialysis was performed for 48 h using methanol as the dialysis fluid, with methanol replaced every 12 h. The solution in the dialysis bag was precipitated dropwise in water and centrifuged. The precipitate was freeze-dried at -60°C and then vacuum-dried at 40°C to obtain 467 mg of a white solid powder with a yield of 48% (DS = 1.82 from IRD- 13 C NMR).

[0077] The preliminarily derivatized cellulose was placed in a 100 mL two-necked flask and vacuumed at 80°C for 2 h. After returning to room temperature, the flask was vacuumed and replaced with nitrogen three times. Then, 15 mL of anhydrous DMAc was added to the reaction flask and stirred until dissolved. After that, 6 mg of dibutyltin dilaurate was added. The temperature was lowered to 0°C, and 0.78 g of pentafluorophenyl isocyanate (3.69 mmol, 3.0 eq., relative repeating units) was added dropwise. The reaction mixture was returned to room temperature and stirred for 2 h. The reaction solution was then slowly heated to 40°C. After a further 14 h of reaction, the reaction solution was dropwise precipitated in methanol with stirring and centrifuged. The precipitate was dissolved in 20 mL of acetone, precipitated again in methanol, and centrifuged. This dissolution-precipitation-centrifugation process was repeated four times until a white solid precipitated. Finally, the precipitate was dissolved in 20 mL of acetone again, dropwise precipitated in a mixture of n-hexane / isopropanol = 9 / 1 (v / v), and centrifuged. The precipitate was dried under vacuum at 40°C for 24 h to obtain 620 mg of white solid powder with a total yield of 64%. 1 H NMR spectra confirmed that the three hydroxyl groups were derivatized with carbamate groups ( Figure 3 ), IRD- 13 C NMR spectrum showed DS = 2.83 ( Figure 4 ).

[0078] Example 2. Preparation of Cellulose Pentafluorophenylcarbamate Cell-NPhF5

[0079] Method 2: 0.20 g (1.23 mmol, 1.0 eq.) of microcrystalline cellulose (DP=200) was added to a 100 mL two-necked flask and dried under oil vacuum at 90°C for 3 h. The mixture was cooled to 80°C, evacuated, and replaced with nitrogen three times. 14 mL of anhydrous DMAc was added and stirred for 2 h until the mixture became slurry. The mixture was then cooled to room temperature and, under a nitrogen purge, 0.80 g (18.87 mmol) of dried anhydrous LiCl was quickly added. Once the reaction mixture was completely clear, a catalytic amount of DMAP was added, followed by the dropwise addition of 1.17 g of pentafluorophenyl isocyanate (5.54 mmol, 4.5 eq., relative repeating units). The mixture was stirred at room temperature for a further 32 h. The mixture was then dropwise precipitated into a 1 / 1 (v / v) methanol / water mixture under vigorous stirring. The precipitate was separated by centrifugation. The precipitate was dissolved in 15 mL of methanol and placed in a dialysis bag with a molecular weight cutoff of 6000. The dialysis was performed for 48 h using methanol as the dialysis fluid, with methanol replaced every 12 h. The solution in the dialysis bag was precipitated dropwise in water and centrifuged. The precipitate was freeze-dried at -60°C and then vacuum-dried at 40°C to obtain 554 mg of a white solid powder with a yield of 57% (DS = 2.03 from IRD- 13 C NMR).

[0080] Example 3. Preparation of cellulose pentafluorophenyl carbamate cell-NPhF5

[0081] Method 3: 0.20 g (1.23 mmol, 1.0 eq.) of microcrystalline cellulose (DP=200) was placed in a 100 mL two-necked flask and evacuated with an oil pump at 90°C for 3 h. The temperature was lowered to 80°C, evacuated, and replaced with nitrogen three times. 15 mL of anhydrous DMAc was added and stirred for 2 h until the mixture became slurry. The mixture was then cooled to room temperature and, under a nitrogen purge, 0.80 g (18.87 mmol) of dried anhydrous LiCl was quickly added. Once the mixture became completely clear, 6 mg of dibutyltin dilaurate was added to the reaction flask, followed by 1.17 g of pentafluorophenyl isocyanate (5.54 mmol, 4.5 eq., relative repeating units) dropwise. The mixture was returned to room temperature and stirred for 2 h. The reaction mixture was then slowly heated to 40°C. After a further 14 h of reaction, the mixture was dropwise precipitated in methanol with stirring and separated by centrifugation. The precipitate was dissolved in 20 mL of acetone, reprecipitated in methanol, and separated by centrifugation. The above dissolution-precipitation-centrifugation process was repeated four times until a white solid precipitated. Finally, the precipitate was dissolved in 20 mL of acetone and precipitated dropwise in a mixture of n-hexane / isopropanol = 9 / 1 (v / v) and centrifuged. The precipitate was dried in vacuo at 40°C for 24 h to obtain 591 mg of a white solid powder with a yield of 61% (DS = 2.40 from IRD- 13 C NMR).

[0082] Example 4. Preparation of cell-NPhF5 chiral stationary phase chromatography filler

[0083] Dissolve 0.20 g of the cellulose derivative prepared in Example 1 in 6.0 mL of THF. Weigh 0.80 g of surface-amino-modified macroporous silica gel with a particle size of 7 μm into a 50 mL thick-walled eggplant-shaped flask. Evenly add 10 drops (approximately 70 μL) of the cellulose derivative solution to the silica gel using a rubber-tipped dropper. Beat vigorously for 5 minutes, then remove the solvent by rotary evaporation for 5 minutes. Repeat this step until all the solution has been added. After the final beating, rotary evaporation is performed for 4 hours to completely remove the solvent, thereby obtaining the cellulose derivative CSPs filler.

[0084] The preparation steps of CSPs using 5 μm macroporous silica were the same as above.

[0085] Example 5. Preparation of chiral chromatographic column based on cell-NPhF5 CSPs and HPLC test

[0086] A chiral chromatographic column was prepared using an RPL-ZD10 column packing machine from Dalian Ripuli Co., Ltd. 1.00 g of CSPs filler (7 μm surface-amino-coated macroporous silica gel coated with a cellulose derivative) prepared in Example 4 was added to approximately 25.0 mL of a 90 / 10 (v / v) mixture of n-hexane / isopropanol and 1.0 mL of liquid paraffin, and uniformly dispersed by sonication for 1 second. The packing pressure was set to 40 MPa, and the column was flushed with a 90 / 10 (v / v) mixture of n-hexane / isopropanol and checked for leaks. Subsequently, the CSPs filler was evenly packed into a 25 cm long, 0.21 cm inner diameter stainless steel chromatographic column, with 200.0 mL of effluent used as the standard for completion.

[0087] The prepared chiral column was installed on a JASCO PU-2089 pump, AS-2055 autosampler, CD-2095 detector, and UV-2070 detector for HPLC analysis. The mobile phases were n-hexane / isopropanol = 90 / 10 (v / v) or n-hexane / isopropanol = 99 / 1 (v / v); the flow rate was 0.1 mL / min; the sample concentration was 0.5-2.5 mg / mL; and the detection wavelength was 254 nm or 232 nm. The theoretical plate number of the prepared chiral column was determined using benzene as a standard, with a plate number greater than 1500 considered acceptable. The dead time (t0) of the tri-tert-butylbenzene peak was used as the peak elution time. The retention factor k1 and separation factor α of the separated substrates were calculated using k1 = (t1–t0) / t0, k2 = (t2-t0) / t0, and α = k2 / k1.

[0088] Example 6: Study on the chiral separation performance of cell-NPhF5 CSPs for 9 standard substrates under different chromatographic conditions

[0089] 9 standard substrates (benzoin, 2,2,2-trifluoro-1-9-anthraceneethanol, cobalt acetylacetonate, Base, diphenylethylene oxide, flavonoids, 2,2-dimethyl-1-phenyl-1-propanol, 2-phenylcyclohexanone, and 1,1-bi-2-naphthol) were prepared into a solution of approximately 1.0 mg / mL in n-hexane / isopropanol = 90 / 10 (v / v). The detection wavelength was set at 254 nm, the flow rate was set at 0.1 mL / min, and the mobile phases were n-hexane / isopropanol = 90 / 10 (v / v) and n-hexane / isopropanol = 99 / 1 (v / v), respectively. The chiral recognition and separation capabilities of the cell-NPhF5 CSPs prepared in Examples 4 and 5 for nine standard substrates were tested.

[0090] The statistical results of the chiral recognition data in different mobile phases obtained in this example are shown in Table 1, and the relevant HPLC spectra are shown in Figure 9 and Figure 10 .

[0091] Table 1 Chiral recognition results of cellulose derivative cell-NPhF5 CSPs on 9 standard substrates

[0092]

[0093] Note: Detection wavelength: 254 nm, flow rate: 0.1 mL / min

[0094] From the data in Table 1, it can be seen that the cellulose derivative cell-NPhF5 CSPs of the present invention can chirally recognize compound 2 (2,2,2-trifluoro-1-9-anthraceneethanol), compound 4 (1,1-bi-2-naphthol), compound 6 ( base), compound 7 (diphenylethylene oxide) and compound 9 (flavonoid).

[0095] Example 7: Study on the chiral recognition and separation performance of cell-NPhF5 CSPs for β-gingerene and β-bisabolene

[0096] (1) The racemates of β-gingerene and β-bisabolene were prepared according to the methods described in the literature (US, US20140161764A1.2014-06-12; Synth. Commun. 1994, 24, 3167.), which are not described in detail in the present invention. The obtained products were all colorless oily liquids.

[0097] (2) 5.0 mg of β-gingerene and β-bisabolene were weighed and dissolved in 2 mL of n-hexane. The detection wavelength was set to 232 nm, the flow rate was 0.1 mL / min, and the mobile phase was n-hexane / isopropanol = 99 / 1 (v / v). The chiral recognition and separation ability of the cellulose derivative cell-NPhF5 CSPs with π-hole bond donor side groups prepared in Examples 4 and 5 for non-polar electron-rich sesquiterpenoid compounds was tested.

[0098] In this example, the chiral recognition and separation results of the representative non-polar sesquiterpenes β-gingerene and β-bisabolene by cell-NPhF5 CSPs are shown in Figure 2. Figure 11 As shown in a and b.

[0099] Example 8. Characterization of the chiral recognition and separation performance of cell-NPhF5 CSPs for 1,1'-dimethylbinaphthyl and methylcyclopropylbenzene

[0100] In this example, the recognition and separation capabilities of the cell-NPhF5 CSPs prepared in Examples 4 and 5 for representative non-polar chiral aromatic substrates were studied. The specific operation method is as follows:

[0101] (1) The substrate was purchased from J&K Company and purified by column chromatography (200-300 mesh silica gel) using n-hexane as eluent before use.

[0102] (2) The purified substrate obtained in step (1) was prepared into a 1.0 mg / mL n-hexane solution, the detection wavelength was set to 254 nm, the flow rate was set to 0.1 mL / min, and the mobile phase was n-hexane / isopropanol = 99 / 1 (v / v). The chiral recognition and separation ability of cell-NPhF5CSPs for chiral non-polar aromatic hydrocarbons 1,1'-dimethylbinaphthyl and methylcyclopropylbenzene was characterized.

[0103] The chiral recognition and separation performance of cell-NPhF5 CSPs for representative non-polar aromatic hydrocarbons in this example are characterized as follows: Figure 11 As shown in c and d.

[0104] Example 9: Study on the chiral recognition and separation performance of cell-NPhF5CSPs for Lewis base drugs with complex structures

[0105] In this example, the recognition and separation capabilities of the cell-NPhF5 CSPs prepared in Examples 4 and 5 for representative complex chiral Lewis base drugs warfarin, praziquantel, aminoglutethimide, bupivacaine, amlodipine, felodipine, azelnidipine, mirtazapine, chlorpheniramine, propranolol, citalopram, and nefopam were studied. The specific operation method is as follows:

[0106] The chiral Lewis base drug was prepared into a 0.5 mg / mL mixture of n-hexane / isopropanol = 3 / 1 (v / v). The detection wavelength was set to 254 nm, the flow rate was 0.1 mL / min, and the mobile phase was n-hexane / isopropanol = 90 / 10 (v / v). The chiral recognition and separation ability of cell-NPhF5 CSPs for the above Lewis base drug was characterized.

[0107] The chiral recognition and separation data of representative Lewis base drugs by cell-NPhF5 CSPs in this example are shown in Table 2. The relevant HPLC spectra are shown in Table 2. Figure 12 .

[0108] Table 2 Chiral recognition results of cell-NPhF5 CSPs for Lewis base drugs with complex structures

[0109]

[0110]

[0111] Note: Mobile phase: n-hexane / isopropanol = 90 / 10 (v / v), detection wavelength: 254 nm, flow rate: 0.1 mL / min

[0112] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that further improvements can be made to the present invention. In short, according to the principles of the present invention, this application is intended to include any changes, uses or improvements to the present invention, including changes that depart from the disclosed scope in this application and are made using conventional techniques known in the art.

Claims

1. A cellulose derivative having a strong π-hole bond donor side group, the structural formula of which is shown below: in, 2. The cellulose derivative according to claim 1, characterized in that The cellulose derivative with a strong π-hole bond donor side group is prepared by an addition reaction between pentafluorophenyl isocyanate and cellulose hydroxyl groups, wherein the side group substitution degree is 2-3.

3. A method for preparing the cellulose derivative according to claim 2, comprising the steps of: Method 1 includes the following steps: (1) Cellulose is dissolved in DMAc / LiCl at a certain temperature, cooled to room temperature, and an excess of pentafluorophenyl isocyanate is added dropwise. The addition reaction between the two is catalyzed by DMAP at room temperature. After the reaction is complete, the product is precipitated with a precipitant, centrifuged, and dissolved again in a good solvent. The product is dialyzed and precipitated again, centrifuged, and dried to obtain a preliminarily derivatized cellulose carbamate derivative. (2) dissolving the preliminarily derivatized cellulose carbamate derivative obtained in step (1) in DMAc, adding a catalyst dibutyltin dilaurate, and dropping an excess of pentafluorophenyl isocyanate at 0°C, then heating to 40°C. After the reaction is completed, precipitating the product with a precipitant, centrifuging, and then dissolving it again with a good solvent, precipitating again, and centrifuging again. Repeating the above steps 3-4 times to completely remove impurities in the cellulose derivative, and drying to obtain a highly substituted cellulose carbamate derivative cell-NPhF5, i.e., a cellulose derivative having a strong π-hole bond donor side group; Method 2 includes the following steps: Without performing step (2) of method 1, the reaction time of step (1) of method 1 is doubled to obtain; Method 3 includes the following steps: Cellulose is dissolved in DMAc / LiCl at 80°C, cooled to room temperature, and a catalyst, dibutyltin dilaurate, is added dropwise at 0°C. An excess of pentafluorophenyl isocyanate is then added and the temperature is raised to 40°C. After the reaction is completed, the product is precipitated with a precipitant, centrifuged, and then dissolved again with a good solvent, precipitated again, and centrifuged. The above steps are repeated 3-4 times to completely remove impurities in the cellulose derivative. After drying, a highly substituted cellulose carbamate derivative, cell-NPhF5, is obtained, that is, a cellulose derivative with a strong π-hole bond donor side group.

4. A HPLC chiral stationary phase (CSPs) material, prepared by coating the cellulose derivative having a strong π-hole bond donor side group according to claim 1 or 2 onto the surface of aminated macroporous silica gel.

5. A method for preparing the HPLC chiral stationary phase (CSP) material according to claim 4, comprising the steps of: dissolving the cellulose derivative having strong π-hole bond donor pendant groups in THF, adding the resulting solution dropwise to surface-aminated macroporous silica gel, mixing, and removing the solvent to completely coat the silica gel surface with the cellulose derivative having strong π-hole bond donor pendant groups, thereby obtaining coated CSPs.

6. A chiral chromatographic column, prepared by packing the HPLC chiral stationary phase (CSPs) material according to claim 4.

7. Use of the cellulose derivative according to claim 1 or 2, the HPLC chiral stationary phase (CSPs) material according to claim 4, or the chiral chromatographic column according to claim 6 in the efficient recognition and separation of electron-rich chiral substrates.

8. The use according to claim 7, characterized in that The electron-rich chiral substrate is a non-polar / weakly polar electron-rich chiral substrate selected from: 1) non-polar / weakly polar terpenes; 2) non-polar aromatic hydrocarbons; 3) at least one of complex structure chiral Lewis bases.

9. The use according to claim 7 or 8, characterized in that The electron-rich chiral substrate is selected from: Alkali, flavonoids, diphenylethylene oxide, binaphthol, trifluoro-1-9-anthracenethanol, β-gingerene, β-bisabolene, 2-methylcyclopropylbenzene, 1,1'-dimethylbinaphthyl, warfarin, amlodipine, azelnidipine, mirtazapine, nefopam, propranolol.

10. A method for chiral separation of an electron-rich chiral substrate, comprising preparing the electron-rich chiral substrate to be separated into a solution, injecting the solution into the chiral chromatographic column of claim 6, eluting, and performing HPLC separation.

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