Abstract

Four stereoisomeric components were produced during the synthesis of the antidepressant drug (1S, 4S)‐sertraline hydrochloride due to the two chiral carbon centers in its chemical structure, including (1S, 4S), (1R, 4R), (1S, 4R), and (1R, 4S)‐isomer. Stereoselective separation of the target isomer (1S, 4S)‐sertraline from the medicinal reaction mixtures by countercurrent chromatography using hydroxypropyl‐β‐cyclodextrin as the stereoselective selector was investigated. A biphasic solvent system composed of n‐hexane/0.20 mol/L phosphate buffer solution with pH 7.6 containing 0.10 mol/L of hydroxypropyl‐β‐cyclodextrin (1:1, v/v) was selected for separation of cis‐sertraline and trans‐sertraline using reverse phase elution mode and (1S, 4S)‐sertraline was separated with (1R, 4R)‐sertraline using recycling elution mode. A fabricated in‐house analytical countercurrent chromatographic apparatus was used for optimization of the separation conditions. Stationary phase retention and peak resolution were investigated for separation of cis‐sertraline and trans‐sertraline by the analytical apparatus.

An approach to access bioactive thioamides was developed based on elemental-sulfur-promoted C(sp 3 )ÀHa ctivation of methylh eteroarenes.T his transformation could successfully furnish as eries of heterocyclic thioamidesw ith excellent yields and it could be conducted on gram scale with good reaction efficiency.M echanistic studies showedt hat methyl heteroarenes reactedw ith dimethylamine released from DMF to form the desired thioamide through elemental-sulfur-promoted CÀHa ctivation.

No abstract

Off-line comprehensive two-dimensional reversed-phase countercurrent chromatography with high-performance liquid chromatography was investigated in separation of crude ethanol extract from traditional Chinese medicinal herb Polygonum cuspidatum Sieb. et Zucc. Two-dimensional contour plots for countercurrent chromatography with high-performance liquid chromatography was obtained after comprehensive separation was completed. Total peak capacity was evaluated and approximately 810 peaks were obtained through a comprehensive two-dimensional separation. A highly orthogonality of 52.23% and a large separation space occupancy of 88.86% were achieved.Meanwhile, it was found that several components could be well separated by countercurrent chromatography while they could not be separated by high-performance liquid chromatography, and vice versa, which further indicated the orthogonality of the two separation methods. The off-line comprehensive two-dimensional countercurrent chromatography with high-performance liquid chromatography provided a promising and powerful method for separation of complex natural products. K E Y W O R D Scountercurrent chromatography, comprehensive two-dimensional chromatography, high performance liquid chromatography, orthogonality, traditional Chinese medicine