Chiral separations in microemulsion electrokinetic chromatography. Use of micelle polymers and microemulsion polymers

In this study, microemulsions of the chiral surfactant polysodium N-undecenoyl-D-valinate (poly-D-SUV) was utilized for enantiomeric separation by investigating two approaches using polymeric chiral surfactant in microemulsion electrokinetic chromatography (MEEKC). In the first approach, poly-D-SUV was used as an emulsifier surfactant along with 1-butanol and n-heptane. Enantioseparation of anionic or partially anionic binaphthyl derivatives, anionic barbiturates, and cationic paveroline derivatives were achieved by varying the mass fraction of 1-butanol, n-heptane and poly-D-SUV. For anionic or partially anionic analytes, relatively lower mass fractions of n-heptane, and poly-D-SUV were found to give optimum chiral separations as compared to that for cationic solutes. In the second approach, the chiral microemulsion polymer was prepared by polymerizing mixtures of 3.50% (w/w) of sodium N-undecenoyl-D-valinate (D-SUV) and 0.82% (w/w) of n-heptane (core phase) at varying concentration of 1-butanol. After polymerization, the n-heptane and 1-butanol were removed to yield solvent free microemulsion polymers (MPs) which were then utilized for the separation of anionic binaphthyl derivatives and anionic barbiturates. When MPs of D-SUV were utilized for chiral separation, 1.00% (w/w) 1-butanol and 3.50% (w/w) 1-butanol was optimum for enantioseparation of (+/-)-BNP and (+/-)-BOH, respectively. On the other hand, for anionic (+/-)-barbiturates very low concentration of butanol (0.25%, w/w) provided optimum resolution. Compared with micellar electrokinetic chromatography (MEKC), the use of micelle polymers or microemulsion polymers in MEEKC showed dramatic enhancement for resolution of (+/-)-BNP, while this enhancement was less dramatic for other binaphthyls [(+/-)-BOH, (+/-)-BNA] as well as for (+/-)-barbiturates and (+/-)-paveroline derivatives. However, higher separation efficiency of the enantiomers was always observed with MEEKC than in MEKC.     

Polymeric alkenoxy amino acid surfactants: III. Chiral separations of binaphthyl derivatives

Micellar electrokinetic chromatography (MEKC) was investigated for the enantiomeric separations of three binaphthyl derivatives ((+/-)-1,1'-bi-(2-naphthol) (BOH), (+/-)-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BNP), and (+/-)-1,1'-binaphthyl-2,2'-diamine (BNA)) using two recently synthesized chiral polymeric surfactants (polysodium N-undecenoxy carbonyl-L-leucinate (poly-L-SUCL) and polysodium N-undecenoxy carbonyl-L-isoleucinate (poly-L-SUCIL)) in our laboratory. Enantiomeric separation (resolution and selectivity) of the binaphthyl derivatives was influenced by polymerization concentration of the monomeric surfactant, pH, type and concentration of the background electrolyte (BGE) as well as concentration of the polymeric surfactant. Two BGEs (dibasic phosphate and Tris-borate) were compared for this study. The use of dibasic phosphate as BGE in poly-L-SUCL provides baseline resolution of (+/-) BOH and (+/-) BNP, however, no resolution and selectivity at all was observed for (+/-) BNA. A similar approach was adopted with Tris-borate-poly-L-SUCL system at fixed pH 10.1, which resulted in baseline resolution of all three binaphthyl derivatives. Although R(s) of binaphthyl derivatives was always higher and electroosmotic flow (EOF) was always lower using Tris-borate than with dibasic phosphate, the selectivity values for the two buffer systems did not differ significantly. In addition, it was found that poly-L-SUCL provided better enantiomeric resolution and selectivity for (+/-) BOH and (+/-) BNA, while poly-L-SUCIL provided enhanced enantiomeric resolution but similar enantioselectivity for (+/-) BNP. This indicates that the depth of analyte penetration into the palisade layer and the micellar core are responsible for chiral recognition of hydrophobic analyte (e.g., (+/-) BOH, and (+/-) BNA) whereas for moderately hydrophobic analyte (e.g., (+/-) BNP) interaction with the polar head group seems to dictate chiral recognition. Simultaneous enantioresolution of all three binaphthyl derivatives was possible in a single electrophoretic run using either poly-L-SUCL or poly-L-SUCIL. Further comparison of the two polymeric surfactants showed that poly-L-SUCL provided slightly longer analysis time than poly-L-SUCIL but the use of the former polymeric surfactant should be preferred due to its ability to provide complete baseline resolution and higher selectivity of all the three atropisomers with a wider chiral window.     

Polymeric alkenoxy amino acid surfactants: I. Highly selective class of molecular micelles for chiral separation of beta-blockers

Two amino acid-based alkenoxy micelle polymers were synthesized for this study. These include polysodium N-undecenoxy carbonyl-L-leucinate (poly-L-SUCL) and polysodium N-undecenoxy carbonyl-L-isoleucinate (poly-L-SUCIL). The polymerization time and concentration of the synthesized micelle polymers were optimized by (1)H-nuclear magnetic resonance (NMR) and capillary electrophoresis (CE) experiments. Detailed physicochemical properties ((1)H NMR, critical micelle concentration (CMC), optical rotation, partial specific volume, aggregation number, and polarity) were determined, and these molecular micelles were introduced as a pseudostationary phase in micellar electrokinetic chromatography to study the molecular recognition and to develop a method for simultaneous separation of eight chiral beta-blockers. It is found that poly-L-SUCL gives overall better chiral resolution and wider chiral window than poly-L-SUCIL. After optimizing the type of micelle polymer, injection size and temperature, simultaneous separation and enantioseparation of eight beta-blockers were achieved in less than 35 min. A comparison with the amide-type surfactants of the same polar head group and alkyl chain length showed that carbamate-type surfactants always work better than the corresponding amide-type surfactant.     

Comparison of HPLC enantioseparation of substituted binaphthyls on CD‐, polysaccharide‐ and synthetic polymer‐based chiral stationary phases

Retention and enantioseparation behavior of ten 2,2′‐disubstituted or 2,3,2′‐trisubstituted 1,1′‐binaphthyls and 8,3′‐disubstituted 1,2′‐binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on β‐CD, polysaccharides (tris(3,5‐dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans‐1,2‐diamino‐cyclohexane, trans‐1,2‐diphenylethylenediamine and trans‐9,10‐dihydro‐9,10‐ethanoanthracene‐(11S,12S)‐11,12‐dicarboxylic acid CSPs). Normal‐, reversed‐phase and polar‐organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non‐identical groups and a chiral axis in the 1,2′ position had the greatest impact on the enantiomeric discrimination. The 8,3′‐disubstituted 1,2′‐binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose‐based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system.     

Combination of cyclodextrins and polymeric surfactants for chiral separations

A cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) method was applied to the enantioseparation of three binaphthyl derivatives using neutral CDs (i.e., beta- and gamma-CD) in combination with various chiral amino acid-based polymeric surfactants (PSs). Both the D- and L-configurations of poly(sodium N-undecanoyl alaninate), poly(sodium N-undecanoyl leucinate), and poly(sodium N-undecanoyl valinate) (poly(L-SUV)) were synthesized. The retention behavior of the three binaphthyl derivatives under optimum electrophoretic conditions using a single chiral additive (PS or CD) is discussed. In addition, the effect of CD cavity size and stereochemical configuration of polymeric surfactants on selectivity (alpha) and resolution (Rs) was investigated. The enantioseparation of (+/-)1,1'-binaphthyl-2,2'-diamine gave a reversal of enantiomeric order when using beta-CD in combination with any of the three D-configuration PS. However, better enantioseparation is obtained when using the corresponding L-configuration PS with beta-CD. A reversal of migration order (RMO) for the enantiomers of (+/-)1,1'-bi-2-naphthol was observed upon the addition of 10 mM gamma-CD to poly(L-SUV). However, no RMO of (+/-)1,1'-bi-2-naphthol was seen when either beta-CD or gamma-CD was combined with D-PS. The enantiomers of (+/-)1,1'-binaphthyl-2,2'-diyl hydrogen phosphate showed little enantioselective behavior toward the PS alone. However, combined D- or L-PS and beta-CD or gamma-CD systems gave increased Rs and alpha values. The chiral recognition of binaphthyl derivatives observed resulting from the various combinations of two chiral selectors is discussed.     

Novel chiral conjugated macromolecules for potential electrical and optical applications

Optically active 1,1′‐binaphthyl molecules have been used to construct novel chiral dendrimers and linear polymers. Efficient light harvesting effects of the dendrimers have been observed. They have shown enantioselective fluorescence responses in the presence of chiral amino alcohol quenchers. They are potentially useful as fluorescent sensors for the recognition of chiral organic compounds. Linear binaphthyl polymers have shown strong light emitting properties. Their colors of emission can be systematically tuned by incorporating linkers of various conjugation length. A very efficient light emitting diode has been prepared from the binaphthyl‐based conjugated polymers. Nonlinear optical chromophores have been organized in the chiral binaphthyl polymer chains to construct noncentrosymmetric and multipolar materials. These novel propeller‐like polymers have shown significant second‐order nonlinear optical effects.     

Application of polymeric surfactants in micellar electrokinetic chromatography-electrospray ionization mass spectrometry of benzodiazepines and benzoxazocine chiral drugs

Chiral micellar EKC (CMEKC) coupled to ESI-MS using polymeric surfactants as pseudostationary phases is investigated for simultaneous enantioseparation of two benzodiazepines, (+/-)-oxazepam ((+/-)-OXA) and (+/-)-lorazepam ((+/-)-LOR), and one benzoxazocine, (+/-)-nefopam ((+/-)-NEF). First, enantioselectivity and electrospray sensitivity of six chiral polymeric surfactants for all three chiral compounds are compared. Second, using poly(sodium N-undecenoyl-L-leucinate) as pseudostationary phase, the organic modifiers (methanol (MeOH), isopropanol, and ACN) are added into the running buffer to further improve chiral resolution (RS). Next, a CMEKC-ESI-MS method for the simultaneous enantioseparation of two benzodiazepines is further developed by using a dipeptide polymeric surfactant, poly(sodium N-undecenoxy carbonyl-L,L-leucyl-valinate) (poly-L,L-SUCLV). The CMEKC conditions including nebulizer pressure, capillary length, ammonium acetate concentration, pH, poly-L,L-SUCLV concentration, and capillary temperature were optimized to achieve maximum chiral RS and highest sensitivity of MS detection. The spray chamber parameters (drying gas temperature and drying gas flow rate) as well as sheath liquid conditions (MeOH content, pH, flow rate, and ionic strength) were found to significantly influence MS S/N of both (+/-)-OXA and (+/-)-LOR. Finally, a comparative study between simultaneous UV and MS detection showed high plate numbers, better chiral RS, and enhanced detectability with CMEKC-MS. However, speed of analysis was faster using CMEKC-UV.     

联萘衍生物作为手性固定相在高效液相色谱中的应用

光学活性的联萘衍生物以其独特的立体化学性质作为优异的C2轴手性诱导源,已被广泛地应用到不对称催化反应和手性识别中。综述了联萘衍生物作为手性固定相在高效液相色谱中的应用。引用文献54篇。     

Rhodium-catalyzed asymmetric hydroformylation of vinylarenes with novel chiral P,N-ligands derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol

Several new chiral P,N-ligands were prepared from 1,2:5,6-di-O-cyclohexylidene-d-mannitol, 1,1′-binaphthol, and phenyl isocyanate derivatives. Their Rh(I) complexes were applied as catalyst precursors in the asymmetric hydroformylation of vinylarenes. The steric and electronic properties of the phenylcarbamate substituents and the chiral binaphthyl moiety showed remarkable effects on the enantioselectivity and regioselectivity of the reaction. The matching combination of phenylcarbamate and the binaphthyl moiety of the ligand 1,2:5,6-di-O-cyclohexylidene-3-phenylcarbamate-4-[(S)-1,1′-binaphthyl-2,2′-diyl]phosphite-d-mannitol gave 50% ee and an 89/11 b/n ratio (branch-to-normal ratio). A synergic effect between the chiralities of mannitol and the binaphthol moieties was observed. Hydroformylation of the styrene gave the product in 75% ee when 1,2:5,6-di-O-cyclohexylidene-3,4-bis[(R)-1,1′-binaphthyl-2,2′-diyl]phosphite-d-mannitol was used as the chiral ligand.     

Synthesis,optical properties,and spectral stability of chiral dendronized binaphthyl‐containing polyfluorene derivatives

A new kind of chiral dendronized binaphthyl‐containing random polyfluorene derivatives bearing different contents (3.2–14.9 mol %) of Fréchet's polyether dendritic wedges have been designed and synthesized through a versatile Pd‐catalyzed Suzuki polycondensation. Their properties have been investigated by NMR, TGA, DSC, CD, UV–vis, and photoluminescence and compared to those of poly(9,9‐dihexylfluorene) ( PF ). It was found that attachment of Fréchet's dendritic wedges into the main chain enhanced the emission efficiency and thermal stability of the copolymers. Furthermore, different from PF , good to excellent spectral stabilities in the solid state were proven for all the dendronized chiral copolymers after a thermal annealing under air at 200 °C. The second‐generation dendronized polymer P3 bearing about 15 mol % of dendritic pendants exhibited high quantum yields in both solutions and films, and excellent thermal oxidative stability. These results demonstrated that the combination of the twisted nonplanar binaphthyl and the sterically demanding dendron could efficiently suppress the intermolecular packing and aggregation at much lower dendron contents compared to other reported dendronized polyfluorenes. Additionally, the investigation of circular dichroism spectra of these chiral dendronized polymers showed a strong Cotton effect at long wavelength (378–384 nm), indicating that the chirality of binaphthyl unit was transferred to the whole polyfluorene backbone. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 886–896, 2008     

Chiral recognition of binaphthyl derivatives using electrokinetic chromatography and steady-state fluorescence anisotropy: effect of temperature

The effect of temperature on the chiral recognition of binaphthyl derivatives in the presence of poly sodium N-undecanoyl-LL-leucyl-leucinate (poly LL-SULL) is examined using electrokinetic chromatography (EKC) and steady-state fluorescence anisotropy. An examination of the effect of temperature suggests that the chiral recognition of 1,1'-binaphthyl-2,2'-diol enantiomers improves with increasing temperature, whereas lower temperatures resulted in better enantiosolectivity in the case of 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate enantiomers. In addition, steady-state fluorescence anisotropy results show that the anisotropy of the two enantiomers are different when complexed to poly-(LL) SULL. As would be expected, the enantiomer that binds stronger to the chiral pseudostationary phase, as evidenced by EKC experiments, had higher anisotropy values. The results of this study suggest that steady-state fluorescence anisotropy can be used to gain further insight into chiral recognition.     

外消旋萘普生酯类在四种纤维素衍生物手性柱上分离及手性 识别机理研究

在纯聚合物型的纤维素三醋酸酯(CTA)、纤维素三苯甲酸酯(CTB)与涂敷型的CTB、纤维素三(4-甲基苯甲酸酯)(CTMB)四种纤维素衍生手性柱上成功地分离了几种外消旋萘普生酯,研究了流动相组成以及溶质的结构对手性分离的影响,探讨了纤维素衍生物手性固定相对外消旋萘普生酯手性识别的机理,得出溶质在固定相手性空腔中体积大小的适应性,尤其是立体结构上的空间适应性是手性识别的关键,不同的固定相这种适应性有所不同,     

Generation of carbanions through stibine-metal and bismuthine-metal exchange reactions and its applications to precision synthesis of ω-end-functionalized polymers

Generation of carbanions from organostibines and organobismuthines through heteroatom-metal exchange reactions was examined from synthetic and mechanistic viewpoints. The exchange reaction proceeded spontaneously upon treatment with various organometallic reagents, such as alkyl lithiums, tetraalkyl zincates, and alkyl magnesium halides to afford the corresponding carbanions quantitatively. Due to the high reactivity of these heteroatom compounds, the exchange reactions took place exclusively even in the presence of various polar functional groups, which potentially react with organometallic species. The advantage of this method was exemplified by the end-group transformation of living polymers that bear these heteroatom species at the ω-polymer end, prepared by using organostibine and bismuthine-mediated living radical polymerizations. Various polymers that bear polar functional groups and acidic hydrogen-for example, poly(methyl methacrylate), poly(butyl acrylate), poly(N-isopropyl acrylamide), and poly(2-hydroxyethyl methacrylate)-could be used in the exchange reactions, and subsequent trapping with electrophiles afforded the corresponding polymers with controlled molecular weights, molecular weight distributions, and end-group functionalities. Competition experiments showed that organostibines and organobismuthines were among the most reactive heteroatom compounds towards organometallic reagents and that their high reactivity was responsible for the high chemoselectivity in the exchange reaction.     

Enantiomeric separations of binaphthyl derivatives by capillary electrophoresis using N-(2-hydroxydodecyl)-L-threonine as chiral selector: effect of organic additives

The chiral selectivity of a novel amphiphile, N-(2-hydroxydodecyl)-L-threonine (2-HDT), was evaluated for enantiomeric resolution of three binaphthyl derivatives (+/-)-1,1'-bi-2-naphthol, (+/-)-1,1'-binaphthyl-2,2'-diamine, and (+/-)-1,1'-binaphthyl-2,2'-diylhdrogen phosphate (BNP) by micellar EKC. The effects of three organic modifiers, methanol, isopropanol, and acetonitrile, on the separations of enantiomers of these compounds were investigated. Separation of enantiomers could be achieved in relatively dilute solutions of the pure surfactant. However, best separations of enantiomers were obtained only in the presence of 10% v/v acetonitrile. Enantiomeric impurity in nonracemic mixtures of R- and S-forms of BNP was determined.     

（＋）-甲基丙烯酸{2,5-双[4′-（（S）-2-甲基丁氧基）苯基]苯基}酯的合成及其螺旋选择性自由基聚合

设计合成了手性单体（＋）-甲基丙烯酸{2,5-双[4′-（（S）-2-甲基丁氧基）苯基]苯基}酯,并进行了自由基溶液聚合.相比于单体,聚合物的比旋光度有显著的同向增长,且在其圆二色光谱上对应于三联苯侧基以及酯基的吸收区域呈现明显的Cotton效应,说明其主链可能采取某一旋向占优的螺旋构象.研究了聚合条件对聚合物旋光性质的影响.结果表明,采用极性大的芳香族溶剂或增加单体浓度有利于获得旋光度大的聚合物;随聚合温度增加,聚合物旋光度先增加后减小,在80℃时聚合达到最大值.该聚合物比甲基丙烯酸三芳基甲基酯类光学活性螺旋链聚合物具有更好的化学结构稳定性和立体结构稳定性.     

Interactions between gemini surfactants and polymers: thermodynamic studies

Aqueous mixtures containing a homopolymer, poly(vinylpyrrolidone) (PVP), or a hydrophobically modified graft copolymer, HM-pullulan, (PULAU9, where 9 stands for the nominal substitution degree), and different Gemini surfactants have been investigated at 25.0 degrees C. A wide variety of experimental conditions were addressed by changing the amount of polymer and of surfactant. The Gemini surfactants were synthesized, purified, and characterized by routine methods. They differ from each other in polar head groups (two sulfonate-, two quaternary ammonium-, or two arginine-based groups), in alkyl chain length (11 or 12 carbon atoms), and in the distance between the polar head groups. The spacers consist of 2, 3, and 6 methylene units or 3 oxyethylene units. Surface activity and solution calorimetry measurements yield some physicochemical features inherent to micelle formation and polymer-surfactant interactions. The data are supported by ionic conductivity, detecting the critical thresholds and quantifying the modifications in binding associated with critical association (CAC) and micelle formation (CMC*). The Gibbs energy of transfer from the micelles to a polymer-binding site, DeltaGtrans, was evaluated from the CAC/CMC* ratios versus the amount of added polymer. A similar procedure determined the enthalpy of transfer, DeltaHtrans. DeltaGtrans decreases with added polymer, whereas DeltaHtrans becomes more negative on increasing the amount of polymer in the medium. According to the selected data presented here, cationic Geminis do not interact with PVP, while significant interactions have been observed in other surfactants. In mixtures with PULAU9, the interaction is significant for all Geminis. This effect is due to interactions between the surfactants and the hydrophobic alkyl groups on the main polymer chain. The pendent groups facing away from the polysaccharide chain act as binding sites for aggregates onto such polymers.     

Electrically driven microseparation methods for pesticides and metabolites: IV. Effects of the nature of fluorescent labels on the enantioseparation of pesticides and their degradation products by capillary zone electrophoresis with UV and laser-induced fluorescence detection

Three different fluorescent tags, namely 5-aminonaphthalene-1-sulfonic acid (ANSA), 7-aminonaphthalene-1,3-disulfonic acid (ANDSA), and 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) were evaluated in the precolumn derivatization of some chiral phenoxy acid herbicides, some chiral transformation products of pyrethroid insecticides, and in their subsequent enantiomeric separation by capillary electrophoresis (CE). The electrolyte systems consisted of sodium phosphate buffers containing chiral surfactants such as octylglucoside (OG) or octylmaltoside (OM) at concentrations above the critical micellar concentration (CMC). Among the three different tags investigated, the ANDSA derivatives of the various solutes were more readily enantioseparated than the ANSA and ANTS derivatives. While the tagging with ANSA allowed the enantioseparation of a limited number of the chiral solute-ANSA derivatives investigated, the ANTS derivatization yielded derivatives that could not be enantioseparated. The polarity of the three different tags increases by increasing the number of sulfonic acid groups in the molecule in the following order: ANSA (one sulfonic acid) < ANDSA (two sulfonic acid groups) < ANTS (three sulfonic acid groups). This seems to indicate that the intermediate polarity of the ANDSA tag allowed more equitable nonpolar/polar interactions of the ANDSA-derivatized solutes with the OG or OM micelles, and consequently the enantioseparation of the solute-ANDSA derivatives. Thus, there is a solute polarity window for enantioresolution with alkylglycoside micelle by CE. Solutes of intermediate polarity that undergo more equitable nonpolar/polar interactions with the micelles exhibited chiral separations.     

Cu-catalyzed enantioselective conjugate addition of diethylzinc to cyclic enones with chiral phosphite ligands derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol

A new and readily in situ prepared catalytic system of copper salts with chiral P,N-ligands or aryl diphosphite ligand, which derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol, 1,1′-binaphthol, and phenyl isocyanate derivatives, were successfully employed in the enantioselective conjugate additions of diethylzinc to cyclic enones with up to 71% ee. Two notable cooperative effects of the stereochemistry of the ligands on the enantioselectivity were observed in the reactions: one between the phenylcarbamate substituent and the axially chiral binaphthyl moiety; another between the stereogenic centers of mannitol and the chiral binaphthol substituents. A significant dependence of the product yield and stereoselectivity on the ring size of the substrate using the ligand 1,2:5,6-di-O-cyclohexylidene-3,4-bis [(S)-1,1′-binaphthyl-2,2′-diyl]phosphite-d-mannitol was also observed: 71% ee for 2-cyclopentenone, 62% ee for 2-cyclohexenone, and 40% ee for 2-cycloheptenone.     

键合型聚丙烯酰胺衍生物手性固定相的制备与手性识别性能

高效液相色谱(HPLC)被广泛认为是分离制备光学纯单一对映体的最有效方法。在高效液相色谱手性拆分中,手性固定相(CSP)的性能直接影响到色谱柱的手性分离能力。在众多手性固定相中,键合型手性固定相具有溶剂耐受性好,分离模式灵活等优点,已经发展成为一类重要的手性固定相。本文通过两步化学反应合成了新型的光学活性丙烯酰胺衍生物--(S)-1-丙烯酰-2-(N-苯基甲酰胺基)吡咯烷((S)-APACP),采用核磁共振氢谱表征了(S)-APACP的化学结构;通过3步化学反应制备了键合型聚丙烯酰胺衍生物手性固定相,采用热重分析法表征了聚合物的键合量,采用HPLC评价了键合型手性固定相的识别能力,分析了影响其手性识别能力的因素。研究结果表明,APACP聚合物成功地键合到硅胶表面制备了具有良好溶剂耐受性的键合型手性固定相,其聚合物键合量为10.2%~11.8%,该键合型手性固定相对若干种对映体显示了较好的手性识别能力。     

Design of chiral organocatalysts for practical asymmetric synthesis of amino acid derivatives

A series of structurally rigid, chiral quaternary ammonium salts and several chiral sec-amine catalysts derived from commercially available (R)- or (S)-binaphthol have been designed as new C(2)-symmetric chiral phase-transfer catalysts and chiral bifunctional amino-catalysts. These chiral organocatalysts have been successfully applied to the highly practical asymmetric synthesis of various amino acid derivatives.