Stereocontrolled Synthesis of trans/ cis-2,3-Disubstituted Cyclopropane-1,1-diesters and Applications in the Syntheses of Furanolignans.

A new Michael addition/intramolecular alkylation sequence of ( Z)-3-(2-bromo-3-arylacryloyl)oxazolidin-2-ones and malonates was developed. By a simple switch of the reaction conditions including the base promoter, solvent, and reaction temperature, both of the cis- and trans-isomers of a series of oxazolidinone-containing 2,3-disubstituted cyclopropane-1,1-diesters could be obtained in good-to-excellent yields and with an excellent diastereoselectivity. The utility of the cyclopropane products was demonstrated in the diastereoselective syntheses of (±)-urinaligran and a stereoisomer of (±)-virgatusin involving the AlCl-promoted [3+2] annulation with veraldehyde or piperonal as the key step.

[Rapid characterization of chemical constituents in capillary wormwood extract based on UHPLC-LTQ-Orbitrap].

A rapid and sensitive UHPLC-HR-MSn method was developed for the identification of chemical constituents in capillary wormwood extract. ACQUITY UHPLC HSS T3 chromatography column (2.1 mm×100 mm, 1.

Levels and Sources of Organochlorine Pesticides in Surface Sediment from Anhui Reach of Huaihe River, China.

Twenty-two organochlorine pesticides (OCPs) were investigated in Anhui reach of Huaihe river, China. Seventeen out of 22 OCPs were detected by GC-MS. The mean concentrations of OCPs followed the order: HCHs > DDTs > HCB > chlordanes > endosulfans.