Synthesis of oxazolidinedione derived bicalutamide analogs

The synthesis of chiral oxazolidinedione derived bicalutamide analogs has been discussed.     

Zur Struktur zweier Arsen- und Antimontricarboxylate

Zusammenfassung Arsen-tris(2,2-dimethylpropionat) (1) kristallisiert monoklin in der Raumgruppe P2₁/n mita=926.2,b=2158.6,c=983.7 pm, =94.92° undZ=4. As hat gegenüber O die Koordinationszahl 3+3. Antimontripropionat (2) kristallisiert monoklin in der Raumgruppe P2₁/c mita=930.2,b=863.0,c=1575.2 pm, =90.27 undZ=4. Die Moleküle sind intermolekular zu Ketten verknüpft, wodurch Sb die Koordinationszahl 3+3 (+3) erreicht.

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Structure of arsen(III) and antimony(III) carboxylates

Summary Arsen-tris(2,2-dimethylpropionate) (1) crystallizes monoclinic in the space group P2₁/n witha=926.2,b=2158.6,c=983.7 pm, =94.92°, andZ=4. As has a coordination number of 3+3. Antimony tripropionate (2) crystallizes monoclinic in the space group P2₁/c witha=930.2,b=863.0,c=1575.2 pm, =90.27, andZ=4. The molecules are bridged to chains; therefore, Sb reaches the coordination number 3+3 (+3).

     

Antimontribenzoat

Zusammenfassung Das -Isomer des Antimontribenzoats kristallisiert rhomboedrisch (hexagonale Aufstellung) in der Raumgruppe R3 mita=1944.0 pm,c=422.3 pm undZ=3. Die Moleküle sind parallel zu 001 gestapelt. Sb hat gegenüber O die Koordinationszahl 3+3 (Sb-O: 208 bzw. 256 pm).

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Antimonytribenzoate

Summary The isomer of (C₆H₅CO₂)₃Sb crystallizes rhombohedrally (hexagonal axes) in the space group R3 witha=1944.0 pm,c=422.3 pm, andZ=3. The molecules are stacked parallel to 001; Sb has a coordination number of 3+3 (Sb-O: 208 and 256 pm, resp.).

     

使用手性冠醚及手性柱的HPCE和HPLC法拆分伯胺类药物对映体的对比研究

报道了在缓冲液中添加 1 8-冠 - 6 -四甲酸 (1 8C6 H4 )的高效毛细管电泳法(HPCE)对 8个含氨基的药物进行拆分 ,低 p H值 (2 .0 6 )和较高浓度的 Tris缓冲液(2 0 mmol· L- 1)可加快手性分离。用手性柱 Crownpak CR(+)的高效液相色谱(HPLC)法对与前相同的 8个含氨基药物进行拆分 ,甲醇浓度增大 ,分离度 RS值有所减小。实验结果还表明 ,使用 HPCE法拆分的各物质 RS值大于使用 HPLC法拆分相应物质的 RS值。     

Chiroptical detection. Novel possibilities of its application to enantiomers

Summary Polarimetric and/or circular dichroic detection of enantiomers after liquid chromatography on optically active sorberts has been used for the following purposes: determination of enantiomeric purity in spite of peak overlap, investigation of enantiomerization during chromatography, monitoring of racemizations and recording of circular dichrograms without preparative enrichment of enantiomers. Novel examples for all applications are give. The general prospects for chiroptical detection are discussed.     

Chiral separation of bupivacaine enantiomers by capillary electrophoresis partial-filling technique with human serum albumin as chiral selector

Capillary electrophoresis (CE) is a powerful technique for enantiomer separations due to its intrinsic high separation efficiencies, speed of analysis, low reagent consumption and small sample requirements. However, some chiral selectors present strong background UV absorption providing high detection limits. The present paper deals with the application of the partial-filling technique to the separation of bupivacaine enantiomers by capillary electrophoresis using human serum albumin (HSA) as chiral selector. In this procedure the cationic surfactant cetyltrimethylammonium bromide (CTAB) was used as a dinamic capillary coating in order to reduce the electro-osmotic flow and detect both bupivacaine enantiomers out of the chiral selector plug. Several experimental conditions such as CTAB concentration, pH, HSA concentration and plug length, background electrolyte concentration, temperature and voltage were studied. Under the selected conditions it is possible to detect the separated enantiomers out of the HSA plug in less than 4 min using 50 mM Tris pH 8 as background electrolyte with 50 microM CTAB, at 30 degrees C and using a separation voltage of 25 kV. The proposed methodology was then validated for analytical purposes and applied to the analysis of pharmaceutical preparations commercially available. The results obtained with the proposed methodology were in good agreement with those declared by the manufacturers. The simplicity, sample throughput, accuracy, reproducibility and low cost of the proposed method make it suitable for the control of the enantiomeric composition of bupivacaine in pharmaceuticals.     

Enantiomeric resolution of underivatized small peptides by HPLC with a chiral crown ether stationary phase

Factors influencing the stereoisomeric resolution of underivatized dipeptides and a representative tripeptide on Crownpak (CR) columns have been investigated. The elution order and relative retention suggest that a combination of chiral, steric, and hydrophobic interactions effects the extent of chiral recognition and the retention achieved during separations. Some dipeptides whose amine terminus is located three atoms from the asymmetric center (such as dipeptides of D ,L -glycine) were resolved, but the elution order was the opposite of that expected for the type of Crownpak column used (CR(+)). Peptides containing hydrophobic substituents were strongly retained, but their retention times could be significantly reduced, and detectability improved, by use of gradient elution. Analysis of a commercial sample of D ,L -leucine-D ,L -alanine revealed the stereoisomers to be present in an unexpected quantitative ratio and demonstrated the utility of these separations for quality assurance and quantitative analyses.     

NMR determination of enantiomeric composition of 1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes using Eu(hfc)3

Experimental conditions for determination of enantiomeric composition of 1-substituted 3-aminocarboranes by ¹H and ¹³C NMR spectroscopy using chiral shift reagent Eu(hfc)₃ have been found.     

Chiral separation on achiral stationary phases with different functionalities using β-cyclodextrin in the mobile phase and application to bioanalysis and coupled columns

Summary -cyclodextrin was used in the mobile phase as chiral selector for separating the enantiomers of terbutaline, chlorthalidone and oxazepam. The effect on chiral resolution using e.g. hydrophobic, polar or cation exchanging stationary phases was investigated. Both the chiral separation factor and retention level were affected by the concentration of methanol and -cyclodextrin. The stationary phase had no effect on the chiral separation only on the level of retention. By tuning the concentration of -cyclodextrin and methanol in the mobile phase chiral separation could be obtained on most stationary phases. By changing the stationary phase while adjusting the mobile phase composition to maintain the chiral selectivity, improvements of the selectivity towards e.g. endogenous compounds can be obtained when separating enantiomers in complex matrixes as biological fluids. Further improvement on selectivity can be obtained if coupled columns are used. This is examplified for separation of chlorthalidone and terbutaline enantiomers in biological fluids by coupling an achiral column to another achiral column and using a mobile phase containing -cyclodextrin on the last column.     

Chiral analysis of pollutants and their metabolites by capillary electromigration methods

Chiral separation of enantiomers is one of the most challenging tasks for any analytical technique including CE. Since the first report in 1985 showing the great possibilities of CE for the separation of chiral compounds, the amount of publications concerning this topic has quickly increased. Although chiral electromigration methods have mainly been used for enantioseparation of drugs and pharmaceuticals, they have also been applied to analyze chiral pollutants. This article intends to provide an updated overview, including works published till January 2005, on the principal applications of CE to the chiral analysis of pollutants and their metabolites, with special emphasis on articles published in the last 10 years. The main advantages and drawbacks regarding the use of CE for chiral separation of pollutants are addressed including some discussion on the foreseen trends of electromigration procedures applied to chiral analysis of contaminants.