Addition of optically pure H-phosphinate to ketones: selectivity, stereochemistry and mechanism.

Aromatic methyl ketones and cyclic asymmetric ketones underwent hydrophosphorylation with P-stereogenic H-P species in the presence of potassium carbonate to produce P,C-stereogenic tertiary α-hydroxyl phosphinates in excellent yields with up to 99 : 1 dr. The diastereoselectivity was induced by a reversible conversion of less stable stereomer of product to that of a more stable one via an equilibrium, which was confirmed by aldehyde/ketone exchanging reaction. Toward the exchange, aliphatic or aldehyde carbonyl were more active than aromatic or ketone carbonyls, respectively. The stability difference between the two diastereomers was controlled by the sizes of substituents linking to phosphorus or α-carbon.

[Qualitative fingerprint and quantitative determination of caffeic acid in compound dandelion enema].

OBJECTIVE: To establish a qualitative and quantitative reversed-phase high-performance liquid chromatography (RP-HPLC) with fingerprinting technique for quality control of compound dandelion enema. METHODS: HPLC was utilized for quality assessment of 10 batches of samples. RP-HPLC analysis was performed on a Hypersil BDS C18 column (4.6 mm x 250 mm, 5 microm) with the mixture of acetonitrile (A) and potassium phosphate solution (B) (pH3.2) as the mobile phase in gradient mode. The concentrations of solvent A were 10%, 80% and 80% at 0, 38 and 40 min, respectively. The column temperature was set at 35 degrees C, the flow rate at 0.7 ml/min and the detection wavelength at 254 nm. RESULTS: HPLC fingerprinting was established from the 10 batches, and the data showed 23 characteristic peaks in the compound dandelion enema for use as index peaks for qualitative identification. Comparison of the retention time and the on-line UV spectra of the samples with the chemical standards identified peaks 3, 4 and 8 as protocatechualdehyde, caffeic acid and ferulic acid, respectively. The contents of caffeic acid in the compound dandelion enema ranged between 63.7 and 136.8 microg/ml. CONCLUSION: High specific chromatographic fingerprinting and quantitative measurement of caffeic acid allows rigorous quality control of compound dandelion enema.

[High-performance liquid chromatography combined with mass spectrum analysis for chromatographic fingerprinting of compound dandelion enema].

OBJECTIVE: To identify the active components of compound dandelion enema, a preparation from 7 traditional Chinese herbal drugs for treatment of gynecological diseases. METHODS: Three-dimensional high-performance liquid chromatography (3D-HPLC) was employed to separate the ethyl acetate extract of compound dandelion Enema, and HPLC combined with mass spectrum (MS) analysis used for chromatographic fingerprinting. RESULT: By comparing the ionic fragments of MS and retention time of each peak, the main active components in compound dandelion enema were determined, including caffeic acid, ferulic acid and protocatechualdehyde. CONCLUSION: HPLC coupled with mass spectroscopy can be used for qualitative analysis of compound dandelion enema.

[High-performance capillary electrophoresis for determining caffeic acid content in Fujie enema and Taraxacum mongolicum Hand.-Mazz].

OBJECTIVE: To determine caffeic acid content in Fujie enema and the crude traditional Chinese herbal drug Taraxacum mongolicum Hand.-Mazz. for controlling the quality of the enema at the levels of both the crude drugs and the final product. METHODS: Caffeic acid content in both the enema and the crude drug was determined at 313 nm Using high-performance capillary electrophoresis (HPCE), under the optimized conditions achieved with a fused-silica capillary tube (75 micromx0 cm) and 20 mmol/L borate running buffer (pH=9.18) at a constant voltage of 12 kV and a sampling time of 5 s at 25 degrees Celsius. RESULTS: The calibration curve displayed good linear relationship within caffeic acid concentration range of 10 to 100 microg/ml (r=0.999 2). The regression equation was Y=1002.45X-327.87, and the average recovery was more than 95%. CONCLUSION: HPCE is simple, rapid and sensitive in separation and determination of caffeic acid in Fujie enema and the crude drug of Taraxacum mongolicum Hand.-Mazz.