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A rhodium-catalyzed tandem intermolecular hydroacylation of terminal alkyne-substituted secondary alcohols with chelating aldehydes and deconjugative isomerization of the resulting α,β-unsaturated ketones for the preparation of synthetically valuable 1,4-diketones is developed. Of note, the completely atom-economical protocol can be extended to the alkynyl alcohols with appropriate carbon chain length, from which 1,5-diketone and 1,6-diketone were obtained involving the short-range deconjugative isomerization. Given its robustness, broad substrate scope, and excellent regioselectivity, this approach provides a promising platform for the synthesis of diverse diketones.

A DDQ-mediated tandem reaction of easily available o-hydroxy­aryl enaminones and cycloheptatriene is disclosed. It provides an effective and convenient method for the synthesis of 3-(cycloheptatrienyl)-substituted chromones in moderate to excellent yields with good functional group tolerance; this reaction involves an oxidative coupling and intramolecular annulation pathway.

Two new nor-lignans, pulvin A (1) and moellenoside C (2), along with two known compounds (3–4) were isolated from the whole plant of Selaginella pulvinate (Hook. & Grev.) Maxim. The structures of t...

An oxidative annulation for the synthesis of 2,4-diarylquinolines from o-allylanilines is disclosed that uses recyclable reagent Chloranil­ as the oxidant. The corresponding products are obtained in moderate to excellent yields. Furthermore, a one-pot access to 2,4-di­aryl­quinolines from easily available anilines and 1,3-diarylpropenes is described as a highly atom-efficient protocol that involves oxidative coupling, rearrangement, and oxidative annulation.

Mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), a novel oxidative coupling of hydrazones and 1,3-diarylpropenes has been disclosed to generate appealing β,γ-unsaturated hydrazones, which further undergo 5-exo-trig or 6-endo-trig cascade cyclization to give the respective 1,2-dihydropyridazines or pyrazoles selectively under metal-free conditions. The mechanisms of the coupling and subsequent cyclization are proposed.

A sensitive capillary electrophoresis strategy was developed by combining salting-out assisted liquid-liquid extraction and online three-step stacking to detect trace quantities of antitumour indole alkaloids in complex biological samples. The proposed strategy fully exploits these two technologies such that extraction, online stacking and separation are combined in a fast and efficient manner. First, salting-out assisted liquid-liquid extraction was used to extract three indole alkaloids (vinblastine sulfate, catharanthine sulfate and vindoline) from complex biomasses. An appropriate volume of acetonitrile (ACN) was mixed with a faecal aqueous solution to precipitate proteins. The mixed solution was vortexed, followed by the addition of ammonium sulfate ((NH

3-Phenyllactic acid is an antimicrobial compound with broad-spectrum activity against various bacteria and fungus. The observed difference in pharmacological activity between optical isomeric 3-phenyllactic acid necessitates a method for enantioseparation. Chiral ligand exchange countercurrent chromatography was investigated for the enantioseparation of 3-phenyllactic acid with a synthesized chiral ligand. A two-phase solvent system was composed of n-butanol/hexane/water (0.4:0.6:1, v/v/v) to which N-n-dodecyl-l-hydroxyproline was added to the organic phase as chiral ligand and cupric acetate was added in the aqueous phase as a transitional metal ion. The influence factors were optimized by enantioselective liquid-liquid extraction. Baseline enantioseparation of racemic 3-phenyllactic acid by analytical high-speed countercurrent chromatography was achieved. The optical purities of enantiomeric 3-phenyllactic acid reached 99.0%, as determined by chiral high-performance liquid chromatography.

The metal-free cross-dehydrogenative coupling (CDC) reaction and subsequent cyclization of 2-hydroxy-1,4-naphthoquinone (lawsone) and 1,3-diarylpropene promoted by DDQ has been developed. 2-Hydroxy-3-alkyl-1,4-naphthoquinones and pyranonaphthoquinones with potential pharmaceutical applications are obtained in moderate to good yields. The reaction is also compatible for 4-hydroxycoumarins.

A plasma-generated carbon aerosol, with the merits of high surface area, abundant porosity and high crystallinity, is a mass synthesized by-product from direct methane conversion in the production of syngas or hydrogen. In the present work, a carbon aerosol produced by rotating gliding arc (RGA) plasma was firstly incorporated with a commercial sponge to fabricate a highly selective and hydrophobic adsorption material. The properties of the carbon aerosol and its derived sponge were comprehensively characterized. By a simple dip-coating method, the wettability of the pristine sponge was altered, which was attributed to the plasma coating of the carbon aerosol. The modified sponge demonstrated an effective and selective adsorption ability for a wide range of oils and solvents, with the maximum adsorption capacity of up to 86 times its own weight. Moreover, the used sponge could be easily recovered by simple evaporation or manual squeezing, while maintaining approximately 100% of its starting adsorption capacity over 5 adsorption-recovery cycles. Such a plasma carbon aerosol coated sponge exhibits a great prospect as a cost-efficient, recyclable and scalable material in separation and adsorption for water treatment.

To promote the detection sensitivity of neutral analytes, a sensitive two-step stacking strategy by coupling field-enhanced sample injection and micelle to cyclodextrin stacking in reverse migrating micelles MEKC has been established by selecting jujuboside A and B as models. The stacking mechanism, affecting factors as well as analytical performances of the proposed method were investigated. Compared with typical injection, the sensitivity enhancement factors of this method were up to 140- and 152-fold for jujuboside A and B, respectively. The enhancements were 8–10 times better than only single stacking strategy by MCDS. The LODs were 0.2–0.3 μg mL−1, interday and intraday%RSD were both lower than 4.3%, and a good linearity (r>0.999) was obtained. Feasibility in real samples analysis was evaluated by using Semen Ziziphi Spinosae dispensing granule and rat's urine. The results suggested that the strategy was simple, reliable, sensitive and promising for the analysis of neutral analytes in complex sample matrix.

Selective separation of chemical components from seven kinds of volatile oil by countercurrent chromatography with three types of cyclodextrins as selective reagent was investigated in this work. Preparative separation of chemical components from volatile oil is generally quite challenging due to their extremely complexity of the composition. A biphasic solvent system n-hexane-0.10 mol L(-1) cyclodextrin (1:1, v/v) was selected for separation of components from volatile oil and three types of cyclodextrins were investigated, including β-cyclodexrin, methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin. All kinds of volatile oils are from seven kinds of traditional Chinese herb. Results showed that some chemical components could be well separated with high purity from each kind of volatile oil using different type of cyclodextrin as selective reagent. For example, germacrone and curcumenone could be selectively separated from volatile oil of Curcumae Rhizoma with methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin as selector respectively, and other five components were selectively separated from volatile oil of Chuanxiong Rhizoma, Myristicae Semen, Aucklandiae Radix and Angelicae Sinensis Radix by countercurrent chromatography with different cyclodexrin as selective reagent. Separation mechanism for separation of components from volatile oil by countercurrent chromatography with cyclodextrin as selective reagent was proposed. Peak resolution of the present separation method could be greatly influenced by the chemical compositions of volatile oil.

Catalyzed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and sodium nitrite, the coupling reaction of 1,3-diarylpropynes and 1,3-dicarbonyl compounds using molecular oxygen as a terminal oxidant was developed. The reaction was promoted dramatically in the presence of HCOOH. The corresponding products were obtained within half an hour in 37–87% yields.

Sertraline is an antidepressant in a group of drugs called selective serotonin reuptake inhibitors. Four stereoisomeric compounds would be produced in its synthetic preparation due to two chiral carbons on its chemical structures. In the present work, stereoselective liquid-liquid extraction of isomeric sertraline with substituted cyclodextrins as stereoselective extractant was investigated. Factors affecting the distribution performance, including organic solvents, types of extractants, pH value, buffer solution of aqueous phase, concentration of extractant and temperature, were investigated. Under optimized conditions, a stereoselectivity of 1.404 was obtained for cis-sertraline and a stereoselectivity of 2.373 was obtained for trans-sertraline when hydroxypropyl-β-cyclodextrin was used as the stereoselective extractant, and a stereoselectivity of 1.685 was achieved for trans-sertraline with methyl-β-cyclodextrin as extractant. An unusual stereoselective combination was observed for trans-sertraline and cis-sertraline when sodium carbonate buffer was used. Successful stereoselective separation of trans-sertraline and cis-sertraline, (1S, 4R) and (1R, 4S)-sertraline by analytical countercurrent chromatography with methyl-β-cyclodextrin as stereoselective selector was achieved, using a biphasic solvent system composed of n-hexane : 0.1 mol L−1 citrate buffer solution with pH7.6 (1:1, v/v).

Racemic trans-paroxol, trans-N-methylparoxetine and trans-paroxetine containing two chiral centres were stereoselectively separated using countercurrent chromatography with hydroxypropyl-β-cyclodextrin as the chiral selector. A two-phase solvent system composed of n-butyl acetate and 0.1 mol L−1 sodium carbonate-sodium bicarbonate buffer at pH 9.2 (1:1, v/v) was selected, and 0.10 mol L−1 hydroxypropyl-β-cyclodextrin was added to the aqueous phase as the chiral selector. Racemic trans-N-methylparoxetine and racemic trans-paroxol (20 mg of each) were stereoselectively separated by countercurrent chromatography in an individual run, yielding 7.1–8.3 mg of enantiomers with a purity of 95–98%, where the recovery of each separated isomer reached approximately 70–83%. Racemic trans-paroxetine (20 mg) was stereoselectively separated by countercurrent chromatography using a recycling elution mode with a biphasic solvent system composed of n-hexane: n-butyl acetate: 0.1 mol L−1 sodium carbonate-sodium bicarbonate buffer at pH 9.2 (9:1:10, v/v/v), and 0.10 mol L−1 hydroxypropyl-β-cyclodextrin was added to the aqueous phase as the chiral selector, yielding 5.0–5.6 mg of enantiomer with a high purity of over 98–99%.

Catalyzed by DDQ and NaNO2, the oxidative coupling between benzylic compounds and 1,3-dicarbonyls in the presence of molecular oxygen and HCOOH was developed. The 1% catalytic amount of DDQ is enough to complete the reaction. This system shows high efficiency and the coupling products are obtained in good to excellent yields within half an hour.

An efficient amidation has been developed of 1,3-diarylpropenes by carboxamides, sulfonamides, carbamates and anilines catalysed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and benzoyl peroxide with molecular oxygen. The corresponding products were obtained in moderate to good yields.

Four β-adrenergic blocking agents, including 1-[(1-methylethyl)amino]-3-phenoxy-2-propanol (1), 1-[(1-methylethyl)amino]-3-(3-methylphenoxy)-2-propanol (2), 1,1′-[1,4-phenylenebis(oxy)]bis[3-[(1-methylethyl)amino]-2-propanol (3) and 1,1′-[(4-methyl-1,2-phenylene)bis(oxy)]bis[3-[(1-methylethyl)amino]-2-propanol (4), were stereoselectively separated by countercurrent chromatography using di- n -hexyl l -tartrate and boric acid as chiral selector. The compounds (3) and (4) have four optical isomers since they contained two chiral centers. A two-phase solvent system composed of chloroform-0.05 mol L −1 of acetate buffer containing 0.10 mol L −1 of boric acid (1:1, v/v) was selected, in which 0.10 mol L −1 of di- n -hexyl l -tartrate was added in the organic phase as chiral selector. 20–42 mg of each racemate was stereoselectively separated by countercurrent chromatography in a single run with high purity of 96–98%, and the recovery of each separated compound reached around 87–93%. This is the first time report on successful stereoselective separation of optical isomeric compounds containing two chiral centers by countercurrent chromatography. At the same time, a chiral stationary phase was screened for analytical stereoselective separation of compounds (3) and (4) by high performance liquid chromatography.

The separation of ten epimeric aromatic acid (–)-menthol esters by countercurrent chromatography with hydroxypropyl-β-cyclodextrin as the mobile phase additive was investigated, and methods for the analysis of all the epimeric esters by reversed-phase high-performance liquid chromatography were established. A biphasic solvent system composed of n-hexane/20–70% methanol containing 50 mmol L−1 of hydroxypropyl-β-cyclodextrin (1:1, v/v) was selected, which provided high separation factors for five of the epimeric esters, and successful separations by countercurrent chromatography were achieved. The complete separation of five pairs of epimeric ester was obtained with the purity being over 98% for each peak fractions, as determined by high-performance liquid chromatography. The recovery of each analyte from the eluted fractions reached around 80–88%. This article is protected by copyright. All rights reserved

This work concentrates on the separation mechanism and application of chiral ligand exchange high-speed countercurrent chromatography (HSCCC) in enantioseparations, and comparison with traditional chiral ligand exchange high performance liquid chromatography (HPLC). The enantioseparation of ten aromatic α-hydroxyl acids were performed by these two chromatographic methods. Results showed that five of the racemates were successfully enantioseparated by HSCCC while only three of the racemates could be enantioseparated by HPLC using a suitable chiral ligand mobile phase additive. For HSCCC, the two-phase solvent system was composed of butanol-water (1:1, v/v), to which N-n-dodecyl-L-proline was added in the organic phase as chiral ligand and cupric acetate was added in the aqueous phase as a transition metal ion. Various operation parameters in HSCCC were optimized by enantioselective liquid-liquid extraction. Based on the results of the present studies the separation mechanism for HSCCC was proposed. For HPLC, the optimized mobile phase composed of aqueous solution containing 6 mmol L−1 L-phenylalanine and 3 mmol L−1 cupric sulfate and methanol was used for enantioseparation. Among three ligands tested on a conventional reverse stationary phase column, only one was found to be effective. In the present studies HSCCC presented unique advantages due to its high versatility of two-phase solvent systems and it could be used as an alternative method for enantioseparations.

The stems of Dendrobium officinale Kimura et Migo, named Tie-pi-shi-hu, is one of the most endangered and precious species in China. Because of its various pharmacodynamic effects, D. officinale is widely recognized as a high-quality health food in China and other countries in south and south-east Asia. With the rising interest of D. officinale, its products have a high price due to a limited supply. This high price has led to the proliferation of adulterants in the market. To ensure the safe use of D. officinale, a fast and convenient method combining normal and fluorescence microscopy was applied in the present study to distinguish D. officinale from three commonly used adulterants including Zi-pi-shi-hu (D. devonianum), Shui-cao-shi-hu (D. aphyllum), Guang-jie-shi-hu (D. gratiosissimum). The result demonstrated that D. officinale could be identified by the characteristic “two hat-shaped” vascular bundle sheath observed under the fluorescence microscopy and the distribution of raphides under normal light microscopy. The other three adulterants could be discriminated by the vascular bundle differences and the distribution of raphides under normal light microscopy. This work indicated that combination of normal light and fluorescence microscopy is a fast and efficient technique to scientifically distinguish D. officinale from the commonly confused species.

The influence of chlorine substituents in chiral separation of three racemic 2-(chlorophenyl)propanoic acids by countercurrent chromatography using hydroxypropyl-β-cyclodextrin as a chiral additive were mainly investigated in the present paper, including 2-(2-chlorophenyl)propanoic acids, 2-(3-chlorophenyl)propanoic acids and 2-(4-chlorophenyl)propanoic acids. The influences of chromatographic conditions on the retention behavior were studied by enantioselective liquid-liquid extraction experiments using the methodology of response surface It was found that 2-(3-chlorophenyl)propanoic acids could be successfully chiral separated by countercurrent chromatography, while no resolution was achieved for racemic 2-(2-chlorophenyl)propanoic acids and 2-(4-chlorophenyl)propanoic acids under optimized separation conditions. The formation of 1:1 stoichiometric inclusion compounds between 2-(3-chlorophenyl)propanoic acids and HP-β-CD was determined by UV spectra measurements. The inclusion constants for 2-(3-chlorophenyl)propanoic acids and HP-β-CD were determined by the Benesi-Hildebrand equation. Meanwhile, the inclusion constants of 2-(3-chlorophenyl)-propanoic acid enantiomer and HP-β-CD were obtained by the pesudophase retention equation in countercurrent chromatography. Furthermore, the inclusion interactions of the three racemates with HP-β-CD were also investigated by the molecular docking. The results obtained from UV spectra measurements and molecular docking showed that the racemate with chlorine substituents in meta-position presented the highest enantiorecognition while the racemates with chlorine substituents in ortho-position had the lowest enantiorecognition. The above results further indicated that forming a stable inclusion complex between racemate and chiral selector is a prerequisite for a successful enantioseparation and at the same time, the difference in inclusion capacity between the two enantiomers is also essential for the enantioseparation.

High performance liquid chromatography (HPLC) and high speed counter-current chromatography (HSCCC) were applied and compared in enantioseparation of 2-phenylpropionic acid (2-PPA) when hydroxypropyl-β-cyclodextrin (HP-β-CD) was used as chiral mobile phase additive. For HPLC, the enantioseparation was achieved on ODS C18 reverse phase column and the mobile phase was 25 mmol L−1 HP-β-CD aqueous buffer solution (pH4.0, adjusted with triethylamine): methanol: glacial acetic acid (85:15:0.5 (v/v/v)). For HSCCC, the two-phase solvent system was composed of n-hexane-ethyl acetate-0.1 mol L−1 phosphate buffer solution pH2.67 (5:5:10 for isocratic elution and 8:2:10 for recycling elution (v/v/v)) added with 0.1 mol L−1 HP-β-CD. The key parameters, such as a substitution degree of HP-β-CD, the concentration of HP-β-CD, pH value of the aqueous phase and the temperature were optimized for both separation methods. Using the optimum conditions a complete HSCCC enantioseparation of 40 mg of 2-propylpropionic acid in a recycling elution mode gave 15–18 mg of (+)-2-PPA and (-)-2-PPA enantiomers with 95–98% purity and 85–93% recovery.

This paper concentrates on the enantioseparation of racemic 2-(substituted phenyl)propanoic acids by high-speed countercurrent chromatography with substituted β-cyclodextrin as the chiral selector, and an investigation of the influence of the substituent on the benzene ring in enantiorecognition between the chiral selector and enantiomer of each racemate is presented. This is an extension research of our previous work on the enantioseparation of 2-phenyl propanoic acid derivatives, to investigate the relationship between the value of enantioseparation factor and the different substituent on the benzene ring. In total, ten racemic 2-(substituted phenyl)propanoic acids were investigated, of which four including 2-(4-nitrophenyl)propanoic acid, 2-(4-methylphenyl)propanoic acid, 2-(4-hydroxyphenyl)propanoic acid, and 2-(4-chlorophenyl)propanoic acid, were studied by countercurrent chromatography for the first time, and two racemates were successfully enantioseparated. The distribution ratio and enantioseparation factor for all the ten racemates were determined by enantioselective liquid-liquid extraction. The results showed that an electron-donating group on the benzene ring presents a higher enantiorecognition induced by chiral selector than that of racemates with an electron-withdrawing group on the benzene ring.

The equilibrium model in enantioseparation of mandelic acid by chiral ligand exchange countercurrent chromatography was investigated using N-n-dodecyl-l-proline as chiral ligand and cupric ion as central metal. Important parameters, including physical partition coefficient and formation constants of binary and ternary coordination complexes in the two-phase solvent system, were determined. This equilibrium model could give an excellent prediction of distribution ratio and enantioseparation factor of the analyte in the biphasic solvent system, which was further verified by experiments. All the average relative deviations were less than 12%, indicating that the established model could provide a simple computational approach for optimization of enantioseparation conditions in chiral ligand exchange countercurrent chromatography.

Counter-current chromatography (CCC) was applied for preparative enantioseparation of three β-blocker drugs, including propranolol, pindolol and alprenolol. The two-phase solvent system was composed of chloroform-0.05 mol L(-1) acetate buffer containing 0.10 mol L(-1) boric acid (1:1, v/v), in which 0.10 mol L(-1) di-n-hexyl L-tartrate was added in the organic phase as chiral selector. Influence factors in the enantioseparation of propranolol were investigated. The chromatographic retention mechanism based on borate coordination complex was proposed. 116 mg of racemic propranolol was completely enantioseparated using conventional high speed CCC in a single run, yielding 48 mg of (+)-propranolol with HPLC purity of 98.9% and 47 mg of (-)-propranolol with HPLC purity of 96.3%. Recovery for propranolol enantiomers from CCC fractions was in the range of 75-82%. pH-zone-refining CCC was also successfully applied in enantioseparation of propanolol and it was found that 356 mg of racemic propranolol could be completely enantioseparated. 145 mg of (+)-enantiomer with HPLC purity of 95.6% and 148 mg of (-)-enantiomer with HPLC purity of 98.2% were recovered from pH-zone-refining mode. Separation mechanism about chiral separation by pH-zone-refining CCC was discussed.

A highly efficient oxidative dimerization of thioamides by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) is reported. The reaction is carried out in ClCH2CH2Cl at room temperature. The corresponding 3,5-disubstituted 1,2,4-thiadiazoles are obtained in good to excellent yields.

Recycling high speed counter-current chromatography (HSCCC) was successfully applied to resolution of (R, S)-naproxen (NAP) using hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector. The two-phase solvent system composed of n-hexane–ethyl acetate–0.1 mol L−1 phosphate buffer solution with pH = 2.67 (8:2:10, v/v/v) was selected. Influence factors for the chiral separation process were investigated, including concentration of HP-β-CD, equilibrium temperature and pH of aqueous phase. Suitable elution mode was selected for HSCCC enantioseparation of (R, S)-NAP. Under optimum separation conditions, 29 mg of (R, S)-NAP was separated using preparative recycling HSCCC with the molar ratio HP-β-CD/NAP racemate 83:1. Technical details for recycling elution mode were discussed as for chiral HSCCC separation. The purities of both (S)-NAP and (R)-NAP were over 99.5% as determined by HPLC. Enantiomeric excess of (S)-NAP and (R)-NAP reached 99.4%. Recovery for NAP enantiomers from HSCCC fractions was 82–89%, yielding 13 mg of (S)-NAP and 12 mg of (R)-NAP.

This work concentrates on a chiral separation technology named biphasic recognition applied to resolution of α-cyclohexylmandelic acid enantiomers by high-speed counter-current chromatography (HSCCC). The biphasic chiral recognition HSCCC was performed by adding lipophilic (−)-2-ethylhexyl tartrate in the organic stationary phase and hydrophilic hydroxypropyl-β-cyclodextrin in the aqueous mobile phase, which preferentially recognized the (−)-enantiomer and (+)-enantiomer, respectively. The two-phase solvent system composed of n-hexane-methyl tert-butyl ether–water (9:1:10, v/v/v) with the above chiral selectors was selected according to the partition coefficient and separation factor of the target enantiomers. Important parameters involved in the chiral separation were investigated, namely the types of the chiral selectors (CS); the concentration of each chiral selector; pH of the mobile phase and the separation temperature. The mechanism involved in this biphasic recognition chiral separation by HSCCC was discussed. Langmuirian isotherm was employed to estimate the loading limits for a given value of chiral selectors. Under optimum separation conditions, 3.5–22.0 mg of α-cyclohexylmandelic acid racemate were separated using the analytical apparatus and 440 mg of racemate was separated using the preparative one. The purities of both of the fractions including (+)-enantiomer and (−)-enantiomer from the preparative CCC separation were over 99.5% determined by HPLC and enantiomeric excess reached 100% for the (±)-enantiomers. Recovery for the target compounds from the CCC fractions reached 85–88% yielding 186 mg of (+)-enantiomer and 190 mg of (−)-enantiomer. The overall experimental results show that the HSCCC separation of enantiomer based on biphasic recognition, in which only if the CSs involved will show affinity for opposite enantiomers of the analyte, is much more efficient than the traditional monophasic recognition chiral separation, since it utilizes the cooperation of both of lipophilic and hydrophilic chiral selectors.

Poly(lactic acid) (PLA) fumed silica nanocomposites were prepared by twin-screw extruder. Thermal properties were investigated by experiments and molecular dynamics simulations. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used and 1.34 °C increase of the glass transition temperature (Tg) and 12 °C improvement of thermal stability were observed for PLA–silica nanocomposites as compared to neat PLA. Molecular dynamics simulations (NPT ensemble) were carried out using modified OPLS-AA force field, and Tg and root-mean-square radii of gyration (Rg) were calculated. A good agreement between the simulation results and experiments was obtained.

pH-zone-refining counter-current chromatography was successfully applied to purify four hydroxyanthraquinones, rhein, emodin, aloe-emodin and chrysophanol, from three crude extracts of Rheum palmatum L.. After the two-phase solvent system methyl tert-butyl ether–tetrahydrofuran–water at an optimized volume ratio of 2:2:3 (v/v) was equilibrated, trifluoroacetic acid (10 mM) was added to the organic phase as a retainer and ammonia (10 mM), sodium carbonate (15 mM) and sodium hydroxide (15 mM) were added to the aqueous phase as the eluter, respectively, for three individual runs. Three separation runs of 1.25, 1.53 and 1.41 g of the three crude samples yielded four hydroxyanthraquinones: 0.70 g rhein, 0.81 g emodin, 0.41 g aloe-emodin and 0.94 g chrysophanol at a high purity of over 99.0, 98.5, 98.2 and 97.8% (determined by HPLC), respectively. The structures were identified by electrospray ionization MS–MS and 1H NMR.

Molecular dynamics simulation has been used to investigate the molecular weight dependence of glass transition temperature for amorphous poly(L-lactide). Amorphous PLLA systems were created using molecular modeling and NPT ensemble MD simulations were carried out using the modified OPLS-AA force field. The molecular weight dependence of glass transition temperature was studied and the good agreement between the simulation results and experiments was obtained.

An oxidative coupling reaction between 1,3-diarylpropenes and propane-1,3-dione derivatives mediated by a catalytic amount of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and azobisisobutyronitrile wi...

An oxidative ether formation between 1,3-diarylpropene and alcohol is catalysed by CuBr/NiCl2 using N-hydroxyphthalimide/O2.

High-speed counter-current chromatography (HSCCC) was applied to isolate and purify bioactive compounds in the essential oil of the rhizomes of Curcuma wenyujin. Two sesquiterpenes germacrone and curdione were successfully isolated and purified using two-phase solvent system composed of petroleum ether-ethanol-diethyl ether-water (5/4/0.5/1, v/v) in tail to head elution mode. 62 mg of germacrone and 93 mg of curdione were obtained from 658 mg of the essential oil each at over 95% purity. Their structures were identified by 1H NMR and EI MS.

The phytochemical investigation of extracts from the root barks of Lycium chinense yielded a new furolactone-type lignan, lyciumin (1). Its structure and absolute configurations were established on the basis of spectral data, particularly by the use of 1D NMR, 2D shift-correlated NMR pulse sequences ((1)H-(1)H COSY, HSQC, HMBC and ROESY) and CD spectra.

A method was established for the enantioseparation of atrolactic acids using high performance liquid chromatography with sulfobutyl ether-beta-cyclodextrin (SBE-beta-CD) as the chiral mobile phase additive, and a C18 reversed-phase column. The influences of the different types of cyclodextrin derivatives, the concentration of chiral mobile phase additive, pH value of the mobile phase, the flow rate and column temperature on the peak resolution were investigated. The separation mechanism for atrolactic acids by high performance liquid chromatography using chiral mobile phase additive, as well as the formation of inclusion complex between SBE-beta-CD and atrolactic acid was studied. In addition, the formation constant was calculated. The enantioseparation was carried out on a reversed-phase column YMC-Pack ODS-A C18 (250 mm x 4.6 mm, 5 microm) with chiral mobile phase consisted of 0.1 mol/L phosphate buffer at pH 2.68 containing 25 mmol/L SBE-beta-CD-acetonitrile (90:10, v/v). The detection wavelength was 220 nm. The flow rate was 0.6 mL/min and the column temperature was 30 degrees C. The retention times of atrolactic acids were 26.65 and 28.28 min, and the peak resolution of 1.68 was achieved. The above established method proves to be a simple and economical way for analytical enantioseparation of atrolactic acid with high peak resolution.

A new coumarin, edgeworic acid (1), was isolated from the flower buds of Edgeworthia chrysantha, together with the five known coumarins umbelliferone (2), 5,7-dimethoxycoumarin (3), daphnoretin (4), edgeworoside C (5), and edgeworoside A (6). Their structures were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences (1H-1H COSY, HSQC and HMBC), in combination with acetylation reactions.

Oxidative desulfurization of secondary or tertiary thioamides (I) provides access to the corresponding amides, while primary thioamides (III) undergo cyclization to afford thiadiazoles (IV).

High speed counter-current chromatography (HSCCC) was successfully applied to resolution of phenylsuccinic acid (PSA) with hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector (CS). The two-phase solvent system composed of n -hexane–methyl tert -butyl ether–0.1 mol L −1 phosphate buffer solution with pH = 2.51 (0.5:1.5:2, v/v/v) was selected. Influence factors involved in the chiral separation were investigated, including the concentration of chiral selector, pH value of the aqueous phase, the separation temperature, and the thermodynamic parameters of inclusion complex were calculated. The complex formation constants were determined using analytical instrument. Two HSCCC elution modes were studied and peak resolution equation was discussed. Under optimum separation conditions, 712 mg of PSA racemate was separated using preparative apparatus. The purities of both of the fractions including (+)-PSA and (−)-PSA from the preparative CCC separation were over 98.5% determined by HPLC and enantiomeric excess of (+)-PSA and (−)-PSA reached 97.6% and 98.6%, respectively. Recovery for the target compounds from the CCC fractions reached 80–82% yielding 285 mg of (+)-PSA and 292 mg of (−)-PSA.

The bioactive compound syringin along with edgeworoside C were separated from the n-butanol extract of the stems and barks of Edgeworthia chrysantha Lindl (E. papyrifera) by high-speed counter-current chromatography (HSCCC) while it was difficult to purify each compound by silica gel column chromatography. Syringin was isolated from this plant for the first time. The two-phase solvent system used was composed of ethyl acetate-ethanol-water at an optimized volume ratio of 15:1:15 (v/v/v). Preparative HSCCC yielded, from 110mg of the partially purified extract, 28mg of syringin and 45 mg edgeworoside C each at over 96% purity by high-performance liquid chromatography analysis. Their structures were identified by electron impact ionization MS, 1H NMR and 13C NMR.