氰醇类化合物对映体的气相色谱分离

对ＣＹＤＥＸ－β全甲基化β－环糊精毛细管柱上，对１４种手性氰醇对映体的乙酰化和三氟乙酰化衍生物，进行了气相色谱分离研究，比较了两种衍生方法的拆分效果，测定了实际合成样品的ｅ．ｅ．值，并对对映体拆分机理进行了一些探讨。     

高效液相色谱手性固定相法直接拆分4种吲哚类衍生物

将纤维素-三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)涂敷于自制的球形氨丙基硅胶上,制备成了纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC-CSP)。利用正相高效液相色谱,在该固定相上对新合成的4种吲哚类衍生物对映体进行了手性拆分。通过选择不同结构和浓度的醇类改性剂,优化了色谱分离条件,同时探讨了醇的结构和浓度对于对映体拆分和保留的影响。结果表明,适合Ⅱ~Ⅳ号样品拆分的醇类改性剂分别为正丁醇、乙醇和乙醇,而适合Ⅰ号样品的醇类改性剂为乙醇和正丙醇组成的混合体系。在优化的各流动相体系下,4种吲哚类衍生物的对映体都得到了很好的分离。在此基础上计算了它们的对映体过量值(e.e.值)。实验结果令人满意,表明高效液相色谱手性固定相法是拆分这类化合物的一种理想方法。     

高效液相色谱-串联质谱法结合多糖衍生物手性固定相拆分氰戊菊酯

建立了以多糖衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分氰戊菊酯对映体的方法。在反相液相色谱条件下,考察了手性固定相的种类、流动相组成、柱温、流速对氰戊菊酯4个立体异构体分离的影响。同时,利用热力学方法对氰戊菊酯的立体异构体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:采用Lux Cellulose-3(纤维素-三(4-甲基苯甲酸酯))手性色谱柱,在以流动相为乙腈-水(5 mmol/L甲酸铵)=(55:45,V:V)流速0.4 mL/min,柱温30℃的条件下,可在14 mins内实现氰戊菊酯4个立体异构体的基线分离。拓展了HPLC-MS/MS在菊酯类手性农药对映体分离及检测上的应用。     

高效液相色谱中的纤维素衍生物手性固定相

评述了高效液相色谱中纤维素衍生物手性固定相直接拆分对映体的进展，介绍了纤维素衍生物的主要类型，纤维素衍生物作手性固定相三种不同方式的特点以及新的纤维素衍生物手性固定相应用，并结合色谱，NMR和分子模型设计和理论计算等方法讨论了纤维素衍生物手性固定的拆分机理。     

反相色谱条件下三唑类手性农药对映异构体的拆分

采用自制的纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC-CSP)和直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(ADMPC-CSP),在反相色谱条件下成功地拆分了己唑醇、烯唑醇、烯效唑、粉唑醇、三唑酮和戊唑醇对映异构体.考察了固定相类型、不同比例的甲醇/水或乙腈/水做流动相、柱温等因素对三唑类手性农药拆分的影响,优化了色谱分离的条件.结果表明:两种固定相都有很强的拆分能力.在优化的色谱条件下,己唑醇和烯唑醇在这两种固定相上都能被分离; 三唑酮只能在CDMPC- CSP上分离;粉唑醇、戊唑醇、烯效唑只能在ADMPC-CSP上分离.流动相中水的含量增加会使对映体的保留增强,分离的可能性增大.在0～40 ℃研究温度范围内,容量因子k随温度的升高而减少,除烯效唑与戊唑醇外,其它手性农药的选择因子α也随温度的升高而减少,而分离度Rs随温度变化没有明显的规律,最好的分离度不都出现在低温.对映体流出顺序用圆二色检测器测定.     

基于直链淀粉衍生物手性固定相的高效液相色谱-串联质谱法拆分4种β-受体阻滞剂对映体及其分离机制的探讨

建立了以直链淀粉衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分普萘洛尔、美托洛尔、阿罗洛尔和卡维地洛4种β-受体阻滞剂对映体的方法。考察了手性固定相的种类、流动相改性剂和添加剂的体积分数、柱温和流速等对4种药物对映体分离的影响。结果表明:在Chiralpak AD-H手性色谱柱上,在正己烷-乙醇-二乙胺(20∶80∶0.03,v/v/v)为流动相、流速0.550 mL/min、柱温40℃的条件下,普萘洛尔、美托洛尔、阿罗洛尔和卡维地洛对映体均达到基线分离,分离度分别为1.37、1.80、2.09和4.70。通过热力学研究及对映体结构分析对拆分机理进行了探讨,发现4种药物对映体的手性拆分均为焓驱动过程,而固定相的手性空腔对不同药物的拆分影响较大。研究结果为β-受体阻滞剂的深入研究提供了参考方法。     

手性流动相添加剂法对两种手性化合物的直接拆分

以β-环糊精为手性流动相添加剂,于C8反相柱上建立了2种手性农药(包括杀菌剂己唑醇和杀虫剂SR-生物丙烯菊酯)对映体的高效液相色谱拆分方法。探讨了β-环糊精浓度、流动相pH、有机改性剂种类等因素对手性拆分的影响。结果表明：在流动相为β-环糊精水溶液、磷酸钠缓冲液(0．05mol／L)、乙腈、三乙胺(体积比50：30：20：0．5)条件下,己唑醇对映体在pH为7．4,β-环糊精溶液浓度为7mmol／L时,SR-生物丙烯菊酯对映体在pH为6．4,β-环糊精浓度为10．5mmol／L时得到最佳分离。     

分子间缩聚制备纤维素手性固定相及其手性拆分性能

以微晶纤维素、3,5-二甲基苯基异氰酸酯和3-(三乙氧基硅)丙基异氰酸酯为原料,通过区域选择法合成了6位带有三乙氧基硅基团的纤维素-二(3,5-二甲基苯基氨基甲酸酯)衍生物,利用三乙氧基硅基团的分子间缩聚将纤维素衍生物高效的固定到硅胶基质上,制备了交联型纤维素手性固定相。在正己烷-异丙醇(体积比4:1),流速1 mL/min,检测波长230 nm时,甲霜灵对映体得到了很好的分离,分离度(Rs)为4.36。此外,还探讨了流动相的配比,不同醇类改性剂对拆分效果的影响,优化了色谱条件。结果表明,交联型纤维素手性固定相对甲霜灵对映体具有较好的手性拆分能力,并且允许使用含有氯仿和四氢呋喃的流动相。     

5种多糖类手性柱分离19种手性多氯联苯的对比研究

采用高效液相色谱在正相条件下对常温稳定存在的19种手性多氯联苯(Polychlorinated biphenyls,PCBs)进行了拆分,对比了5种不同多糖类手性色谱柱的拆分效果.其中Lux Cellulose-1,Cellulose-3和Cellulose-4分离效果较好,在Cellulose-1上PCBs91,136,139,149和171可基线分离,在Cellulose-3上PCBs45,84,88,95,131,135,144和149能够完全分离,在Cellulose-4上PCBs88,131,139,171和174能够完全分离,在以上3种色谱柱上PCBs132,175,176,183,196和197可部分分离,但Cellulose-2和Amylose-2对这19种手性PCBs分离效果很差.考察了温度对拆分的影响,结果在5℃～30℃C之间,PCBs对映体在Cellulose-1和Cellulose-3上对应的范特霍夫方程线性关系较好,而Cellulose-4受柱温影响不稳定.手性PCBs拆分过程整体受焓驱动,温度降低有利于对映体分离.利用在线旋光确定了各PCBs的对映体洗脱顺序,结果表明PCBs对映体的拆分程度和旋光洗脱顺序受苯环上氯原子取代数目和取代位置的影响.     

氟西汀衍生物对映体在纤维素手性固定相上的拆分

用纤维素-三(3,5-二甲苯基氨基甲酸酯)(Chiraleel OD)手性固定相拆分了两种氟西汀衍生物对映体。使用15cm长色谱柱分离NBD-氟西汀衍生物的流动相为四氢呋喃／正己烷(25：75),分离DBD-氟西汀衍生物的流动相为四氢呋喃／正己烷(20：80);流速为1．0mL/min,荧光检测,柱温为室温。醇类改性剂作流动相甚至不能部分拆分氟西汀衍生物。实验考察了四氢呋喃含量和柱长对手性分离的影响,探讨了手性拆分氟西汀衍生物的机理。     

Evaluation of polysaccharide-based chiral stationary phases in quality control of (S)-mirtazapine

High-performance liquid chromatographic methods were developed for separation of the enantiomers of mirtazapine and its four process-related substances. The direct separations were achieved on chiral stationary phases containing amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H), cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and cellulose tris(4-methylbenzoate) (Chiralcel OJ-H ). The experimental data were utilized to discuss the effects of the mobile phase composition, the nature of the alcoholic modifier and the specific structural features of the analytes on retention and separation. The elution sequence was determined under the optimized separation conditions.     

含磷手性化合物在多聚糖类手性固定相上的手性分离

在纤维素 三(3,5 二甲基苯基氨基甲酸酯)(ChiralcelOD)和直链淀粉 三(3,5 二甲基苯基氨基甲酸酯)(ChiralpakAD H)手性固定相上,采用高效液相色谱正相条件,分离了系列含磷手性化合物。考察了流动相中有机改性剂的种类及浓度对手性分离的影响;研究了化合物的结构与保留及对映体选择性的关系;并探讨了手性识别机理。     

Integration of supercritical fluid chromatography into drug discovery as a routine support tool. Part I. fast chiral screening and purification

Supercritical fluid chromatography (SFC) has been implemented within our group as a purity assessment and purification tool to complement high performance liquid chromatography (HPLC) for diastereomer and chiral separations. Using a novel strategy, rapid chiral screening has been implemented using short columns, high flow rates and fast gradients. A primary screen delivers a separation assessment using one solvent modifier (methanol) and four columns (Chiralpak AD-H and AS-H, and Chiralcel OD-H and OJ-H) run serially in a total of 24 min. A secondary screen then uses ethanol and isopropanol (IPA) modifiers across the same columns. The screens can be combined to run a sequence of samples overnight where each racemate is analysed over 80 min. The fast analytical screening and optimisation process enables rapid identification of the purification method. Furthermore, subsequent preparative chiral SFC has decreased the overall sample turnaround time for the Medicinal Chemist, delivering high fraction purities and acceptable recoveries, substantial operational cost savings and increased flexibility with respect to large scale purification feasibility in comparison to HPLC. SFC has been so successful it is now used as the primary method for chiral analysis and purification within our laboratory.     

Comparison of separation performance of polysaccaride-based chiral stationary phases in enantioseparation of 1-(4-chlorobenzhydryl)piperazine benzamide derivatives by HPLC

Analytical high-performance liquid chromatographic enantioseparation of 1-(4-chlorobenzhydryl) piperazine benzamide derivatives was accomplished on different chiral stationary phases. The enantiomers of the compounds were resolved by normal-phase chromatography on silica-based amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H), cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and cellulose tris(4-methylbenzoate) (Chiralcel OJ) columns with mobile phases consisting of mixtures of n-hexane and ethanol in different proportions (90: 10, 80: 20). The mobile phase and the chiral stationary phase were varied to achieve the best resolution. The effect of the concentration of ethanol in the mobile phase was studied. The resolution obtained on the three columns was significant.     

Enantioselective HPLC resolution of synthetic intermediates of armodafinil and related substances

Armodafinil is a unique psychostimulant recently approved by the US Food and Drug Administration for the treatment of narcolepsy. The chromatographic resolution of its chiral intermediates including related substances in the total synthesis of armodafinil was studied on polysaccharide-based stationary phases, viz. cellulose tris-(3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and amylose tris-(3,5-dimethylphenylcarbamate) (Chiralpak AD-H) by HPLC. The effects of 1-propanol, 2-propanol, ethanol, and trifluoroacetic acid added to the mobile phase and of column temperature on resolution were studied. A good separation was achieved on cellulose-based Chiralcel OD-H column compared to amylose-based Chiralpak AD-H. The effects of structural features of the solutes and solvents on discrimination between the enantiomers were examined. Baseline separation with R(s) >1.38 was obtained using a mobile phase containing n-hexane-ethanol-TFA (75:25:0.15 v/v/v). Detection was carried out at 225 nm with photodiode array detector while identification of enantiomers was accomplished by a polarimetric detector connected in series. The method was found to be suitable not only for process development of armodafinil but also for determination of the enantiomeric purity of bulk drugs and pharmaceuticals.     

Supercritical fluid chromatography tandem-column method development in pharmaceutical sciences for a mixture of four stereoisomers

A tandem-column method using Chiralpak AD-H and Chiralcel OD-H columns was achieved for baseline separation of a mixture of chiral pharmaceutical compounds (i.e., four stereoisomers) via supercritical fluid chromatography (SFC) with a mobile phase consisting of 90% liquid carbon dioxide and 10% ethanol:isopropanol (50:50 v/v). On the contrary, this mixture (mixture A) could not be baseline separated by SFC conditions explored with individual Chiralpak AD-H and Chiralcel OD-H columns. The effects of various mobile phases on elution order, capacity factor, selectivity, and resolution were determined with mixture A on the individual aforementioned columns to develop the tandem-column method.     

Chiralpak AD-H和Chiralcel OJ-H手性固定相拆分扁桃酸系列化合物

对比了商品化的淀粉型手性固定相Chiralcel OJ-H和纤维素型手性固定相Chiralpak AD-H柱在正相条件下对扁桃酸系列8个化合物的拆分,结果表明Chiralcel OJ-H柱对扁桃酸系列化合物具有更强的手性识别能力,8个外消旋扁桃酸化合物在36 min内都得到了基线分离。研究发现,扁桃酸苯环上的取代基对其拆分的难易程度影响很大,其电子诱导效应影响扁桃酸类化合物在固定相上的保留时间,其空间位阻效应是扁桃酸在固定相上被拆分成败的决定因素。通过对比分析扁桃酸和手性柱的结构,探讨了可能的手性拆分机理是基于Chiralpak AD-H(Chiralcel OJ-H)手性固定相和扁桃酸系列化合物之间的氢键-氢键、偶极-偶极、π-π电子相互作用以及空间适应性等诸多因素的综合影响,其中空间适应性起到至关重要的作用。本研究可为一些实际光学活性扁桃酸及其类似物的对映体纯度测定与拆分研究提供参考。     

Enantiomeric resolution of new aromatase inhibitors by liquid chromatography on cellulose chiral stationary phases

Analytical HPLC methods using derivatized cellulose chiral stationary phases were developed for the direct enantioseparation of substituted [1-(imidazo-1-yl)-1-phenylmethyl)]-benzothiazolinone and benzoxazolinone derivatives with one chiral center. Those analogues of fadrozole constitute new potent nonsteroidal inhibitors of aromatase (P450 arom). The separations were made using normal phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, or 2-propanol) in various proportions, and a silica-based cellulose tris-3,5-dimethylphenylcarbamate (Chiralcel OD-H), or tris-methylbenzoate (Chiralcel OJ). The effects of concentration of various aliphatic alcohols in the mobile phase were studied. A better separation was achieved on cellulose carbamate phase compared with the cellulose ester phase. The effects of structural features of the solutes along with the temperature of the column on the discrimination between the enantiomers were examined. Baseline separation (Rs > 1.5) was easily obtained in many cases.     

Enantioseparation Using Chitosan Tris(3-chlorophenylcarbamate) as a Chiral Stationary Phase for HPLC

A novel chiral stationary phase (CSP) consisting of a silica-based chitosan tris(3-chlorophenylcarbamate) derivative was used for the enantioseparation of nine racemic compounds in the normal phase mode by high-performance liquid chromatography (LC). The influence of the type and percentage of modifier in the mobile phase on the optimization of the resolution was investigated. The resolution of epoxiconazole using this system was compared with those achieved using commercially available Chiralcel^® OD-H and Chiralpak^® AD-H columns. Among the tested racemates, seven racemic compounds were separated most quickly on the CSP of chitosan tris(3-chlorophenylcarbamate). Baseline or near-baseline separation was achieved for benzoin, penconazole, hexaconazole, and epoxiconazole, while the others were partially separated. The enantioseparation results for epoxiconazole were not inferior to those of commercially available Chiralcel^® OD-H and Chiralpak^® AD-H columns.     

Enantiomeric separation of precursors of rho-kinase inhibitors by HPLC on polysaccharide-based chiral stationary phases

Summary The separation of enantiomers of substituted cyclohexanecarboxamides, benzamides and chemical precursors of Rho-kinase inhibitors was achieved using derivatized polysaccharide-based chiral stationary phases. Separations were by normal phase HPLC with a mobile phase ofn-hexane-alcohol (methanol, ethanol or 2-propanol) in various proportions, and a silica-based cellulose tris-3,5-dimethylphenylcarbamate (Chiralcel OD-H), tris-methylbenzoate (Chiralcel OJ), a silica-based amylose tris-(S)-1-phenylethylcarbamate (Chiralpak AS), or tris-3,5-dimethylphenylcarbamate (Chiralpak AD). The effects of cencentration of various aliphatic alcohols in the mobile phase were investigated. The effect of structural features on the discrimination between the enantiomers was examined. The isolation of milligram amounts of enantiomers of two derivatives was performed on an analytical column by multiple repetitive injections under overload conditions.