ABSTRACT
Chiral carbon-carbon (C-C) and carbon-heteroatom (C-X) bonds are pervasive and very essential in natural products, bioactive molecules, and functional materials, and their catalytic construction has emerged as one of the hottest research fields in synthetic organic chemistry. The last decade has witnessed vigorous progress in Rh(I)-catalyzed asymmetric C-H functionalization as a complement to Rh(II) and Rh(III) catalysis. This review aims to provide the most comprehensive and up-to-date summary covering the recent advances in Rh(I)-catalyzed C-H activation for asymmetric functionalization. In addition to the development of diverse reactions, chiral ligand design and mechanistic investigation (inner-sphere mechanism, outer-sphere mechanism, and 1,4-Rh migration) will also be highlighted.
ABSTRACT
An organocatalytic enantioselective radical reaction of potassium alkyltrifluoroborates, DABCO·(SO2)2 and α,ß-unsaturated carbonyl compounds under photoinduced conditions is developed, which provides an efficient pathway for the synthesis of chiral ß-sulfonyl carbonyl compounds in good yields with excellent enantioselectivity (up to 96% ee). Aside from α,ß-unsaturated carbonyl compounds with auxiliary groups, common chalcone substrates are also well compatible with this organocatalytic system. This method proceeds through an organocatalytic enantioselective radical sulfonylation under photoinduced conditions, and represents a rare example of asymmetric transformation involving sulfur dioxide insertion.
ABSTRACT
OBJECTIVE: To establish a method for determining the content of caffeic acid in compound Yinhuangjiedu decoction using high-performance capillary electrophoresis (HPCE). METHODS: The optimized HPCE for determining caffeic acid content utilized a fused-silica capillary tube (75 microm x 60 cm, effective length of 53 cm) with 20 mmol/L borate as the running buffer (pH=9.18), a constant voltage of 12 kV, a sampling time of 5 s at 25 degrees celsius, and UV detection wavelength at 313 nm. RESULTS: The linear range of caffeic acid was 20-100 microg/ml. CONCLUSION: HPCE is simple, rapid, and sensitive for quality control of the compound Yinhuangjiedu decoction.