Direct Resolution of the Enantiomers of Betaxolol and Related Intermediates, and Its Application

An OJ-H chiral column has been used for direct resolution of the enantiomers of betaxolol and related intermediates in the preparation of (S)-betaxolol. The enantiomers can be excellently resolved (R _S > 2) within 9.4 min with high peak symmetry. The enantiomers of some acetylated intermediates, which cannot be resolved on an OD-H column, can also be resolved. The method is simple and suitable for routine determination of ee values in the preparation of (S)-betaxolol.     

麦草伏甲酯对对映体的高效液相色谱分离

手性分离;麦草伏甲酯对对映体的高效液相色谱分离     

Direct Resolution of Enantiomers in Column Liquid Chromatography

Abstract

Important progress has been performed during the ten past years, in the direct resolution (without derivatization) of enantiomers by column liquid chromatography. Generally chiral packings proceeding from natural or synthetic optically active polymers are used. Complete resolutions of hole families of chiral solutes is obtained in systems involving a steric locking interaction (charge transfer between aromatic substituents, crown ether cavity, crowded complexes with metal ions). For analytical purposes an other proraising way is the use of a classical packing and a chiral mobile phase.     

The Direct Resolution of the Enantiomers of Four Chiral Pesticides

Cellulose-tris(3,5-dimethylphenylcarbamate)(CDMPC) were synthesized as highperformance liquid chromatography (HPLC) chiral stationary phase(CSP). The successful resolution of four chiral pesticides on the CSP was realized and the influence of the temperature on the separation was studied.     

纤维素衍生物手性固定相对戊唑醇对映体的拆分

戊唑醇是三唑类杀菌剂,作用机理为抑制麦角甾醇的生物合成。戊唑醇的化学名称为(R,S)-1-(4-氯苯基)-4,4-二甲基-3-(1H-1,2,4-三唑-l-基甲基)戊醇,结构如图l。它的分子结构中含一个手性碳,具有一对对映异构体。     

酰胺型手性固定相直接拆分克仑特罗对映体

 将酰胺型手性固定相用于正相高效液相直接拆分 β2 受体兴奋剂克仑特罗。讨论了三元流动相中正己烷、1,2 二氯乙烷和甲醇含量的变化以及柱温和流速对分离的影响 ;优化了实验条件 :流动相为V(正己烷 )∶V(二氯乙烷 )∶V(甲醇 ) =5 4∶38∶8,柱温为 17℃ ,流速为 1 0mL/min ;并对拆分的机理加以探讨。方法简单、快速。     

纸色谱法实现对丙氨酸快速手性分离的研究

利用万古霉素配制的浸渍剂制备得到了手性识别试纸,同时基于纸色谱法,使用试纸对手性丙氨酸进行手性分离研究。研究结果表明,该试纸能够对手性丙氨酸实现有效分离。进一步研究了万古霉素浸渍剂浓度和展开剂组成对手性分离效果的影响。运用手性试纸识别和分离手性丙氨酸具有快速、高效、便携等优点,适合用于化学和生物学实验教学,同时具有一定的实际应用价值。     

反式氯氰菊酯对映异构体的分离

反式氯氰菊酯对映异构体的分离;拆分;手性固定相     

苯丙氨酸酯类衍生物对映异构体的拆分

利用手性Ｃｈｉｒａｌｃｅｌ ＯＤ柱高效液相色谱对一系列苯丙氨酸酯类衍生物对映异构体进行了拆分，获得了良好的分离结果。讨论了化合物的结构对拆分效果的影响。     

利用二硝基苯甲酰-苯基甘氨酸型手性固定相直接拆分丙卡特罗药物对映体

用手性源(R)-苯基甘氨酸,采用非对称合成方法制备了3,5-二硝基苯甲酰-(R)-苯基甘氨酸手性固定相(DNB-PG CPS),利用它直接拆分了丙卡特罗药物的部分对映体,取得了良好的拆分效果。以不同比例的异丙醇-正己烷(体积比分别为20∶80,10∶90,5∶95,2∶98)为流动相,对丙卡特罗进行了拆分,其分离因子α的范围为1.54-1.67。此外,还测试了不同流动相组成对分离效果的影响,考察了液固吸附色谱保留值方程lnk＝a+cC b+blnC b中保留因子k和分离因子α与强极性洗脱剂组分b的浓度C     

Direct Resolution of Enantiomers of DL-Amino Acids by Thin-Layer Chromatography with Vancomycin as Impregnating Agent

JPC – Journal of Planar Chromatography – Modern TLC -     

Direct Resolution of Six Beta Blockers into their Enantiomers on Silica Plates Impregnated with l-Asp and l-Glu

JPC – Journal of Planar Chromatography – Modern TLC - Resolution of racemic metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, commonly used ß-blockers,...     

奥美拉唑、兰索拉唑对映体及相关物质在不同手性柱的分离比较

考察了奥美拉唑、兰索拉唑对映体及其拆分剂联二萘酚在4种手性柱（chiralcel OD、chiralpak AD、kromasil CHI-TBB和chiral-AGP)上的色谱行为。实验结果表明：Chiralpak AD、 Chiral-AGP柱分离度大，柱效稳定，并且这两种柱子的配合使用实现了对包结拆分的全过程监控。此外，本文根据对映体在不同手性柱的出峰顺序进行了讨论。     

Determination of the Enantiomers of Tamsulosin Hydrochloride and its Synthetic Intermediates by Chiral Liquid Chromatography

A chiral liquid chromatographic method is described for the determination of the enantiomers of tamsulosin hydrochloride and its synthetic intermediates. Enantioseparation was achieved on a Chiralcel OD-R column (250 mm × 4.6 mm, 10 m) using a mobile phase consisting of a mixture of 0.5 mol L^–1 sodium perchlorate and acetonitrile (80:20, v/v, pH 4.0). The flow rate was 0.4 mL min^–1 and detection was at 223 nm. Excellent enantiomer separations were achieved for tamsulosin hydrochloride and its synthetic intermediates. No other methods are available for the separation of these enantiomers. The method developed in this study has been successfully applied for purity control.     

酰胺型手性固定相反相拆分布洛芬药物对映体

利用酰胺型手性固定相反相拆分了布洛芬对映异构体,用有０．０１ｍｏｌ／Ｌ ＮＨ４Ａｃ的甲醇和水作流动相。在优化分离条件的同时,研究了不同的有机调节和对分离的影响,并探讨了分离的机理。     

Synthesis,Chiral Resolution and Enantiomers Absolute Configuration of 4-Nitropropranolol and 7-Nitropropranolol

We recently identified 6-nitrodopamine and other nitro-catecholamines (6-nitrodopa, 6-nitroadrenaline), indicating that the endothelium has the ability to nitrate the classical catecholamines (dopamine, noradrenaline, and adrenaline). In order to investigate whether drugs could be subject to the same nitration process, we synthesized 4-nitro- and 7-nitropropranolol as probes to evaluate the possible nitration of the propranolol by the endothelium. The separation of the enantiomers in very high yields and excellent enantiopurity was achieved by chiral HPLC. Finally, we used Riguera’s method to determine the absolute configuration of the enantiomers, through double derivatization with MPA and NMR studies.     

Direct Chiral HPLC Method for the Simultaneous Determination of Warfarin Enantiomers and Its Impurities in Raw Material and Pharmaceutical Formulation: Application of Chemometric Protocol

Warfarin is a well-known anticoagulant agent that occurs in two enantiomers, (R)-(+)-warfarin and (S)-(?)-warfarin, in which 4-hydroxycoumarin and benzalacetone are commonly found as impurities. Due to the lack of analytical reports for the simultaneous estimation on warfarin and its impurities in bulk drug and pharmaceuticals, we aim at the simultaneous estimation and optimization of the chromatographic separation of warfarin and its related substances employing experimental design. Central composite design was employed to evaluate the influence of two independent variables (concentration of organic modifier and flow rate) on the output responses: capacity factor (k ₁), resolution of the peak (Rs _3,4), and retention time of the last peak (tR ₅), as well as to model these responses. Further, the central composite design results were combined in a multicriteria decision-making approach in order to obtain a set of optimal experimental conditions leading to the most desirable compromise between resolution and analysis time.     

柠檬醛及中间体的合成

以异戊烯醛和异戊烯醇为原料,经异戊烯酸催化缩醛化反应得到3-甲基-2-丁烯醛二异戊烯基缩醛,再经磷酸二氢铵催化消除反应得到顺/反-异戊二烯基-3-甲基丁二烯醚,并进一步热重排获得柠檬醛。研究了缩醛化反应条件和消除反应条件对转化率的影响。结果表明,以0.3%异戊烯酸为酸性催化剂,70～75℃共沸脱水反应8 h,异戊烯醛的单程转化率达到63%～64%,处理后可得含量为97.5%的3-甲基-2-丁烯醛二异戊烯基缩醛,收率96.8%;以0.2%～0.5%磷酸二氢铵为催化剂,100～130℃,2.66 kPa下反应并及时将反应产物蒸出,处理后得到含量为95.9%的顺/反-异戊二烯基-3-甲基丁二烯醚,收率97.0%。顺/反-异戊二烯基-3-甲基丁二烯醚在120～130℃重排反应1 h,其反应产物柠檬醛含量97.5%,收率90.2%。     

HPLC Analysis of Fungal Melanin Intermediates and Related Metabolites

Abstract

A convenient method to concentrate and separate intermediates and related secondary products of the pentaketide pathway leading to melanin biosynthes is has been developed. Twelve of the fourteen known compounds were separated using reverse phase high performance liquid chromatography with a 12 to 42% linear gradient of acetonitrile in 2% acetic acid. The remaining two, highly water soluble isomers, were isocraticly separated on the same column with 5% acetonitrile in 2% acetic acid. Solid phase extraction and concentration of representitive compounds in acidified aqueous brine was accomplished with reverse phase Sep-Pak cartridges. The effectiveness of the method was evaluated by determining the pentaketides produced by cell-free homogenates of Verticillium dahliae supplied with scytalone as the substrate and by cultures of two V. dahliae mutants. The method has the potential for quantifying all known pentaketide melanin metabolites and thus will allow for more comprehensive studies of fungal melanin biosynthesis.     

加压毛细管电色谱法分离盐酸奥昔布宁对映体

采用加压毛细管电色谱法,以羟丙基-β-环糊精作为手性选择剂,对盐酸奥昔布宁对映体进行手性分离。在优化的试验条件下,16g·L-1羟丙基-β-环糊精为手性选择剂,pH 2.8的乙腈-5mmol·L-1磷酸盐缓冲溶液以体积比60比40混合溶液为流动相,运行电压18kV,毛细管柱温度18℃,盐酸奥昔布宁对映体在14min内成功分离。