Suzuki-Miyaura Coupling Enabled by Aryl to Vinyl 1,4-Palladium Migration.

The Suzuki-Miyaura coupling is a fundamentally important transformation in modern organic synthesis. The development of new reaction modes for new chemical accessibility and higher synthetic efficiency is still the consistent pursuance in this field. An efficient Suzuki-Miyaura coupling enabled by a controllable 1,4-palladium migration was realized to afford stereodefined multisubstituted olefins and 1,3-dienes. The reaction exhibits remarkable broad substrate scope, excellent functional-group tolerance, versatile conversion with obtained products, and easy scalability. The practicality of this method is highlighted by the aggregation-induced emission feature of the produced olefins and 1,3-dienes, as well as the capability of affording geometric isomer pairs with a marked difference on photoluminescent quantum yield values.

Asymmetric Alkenylation of Enones and Imines Enabled by A Highly Efficient Aryl to Vinyl 1,4-Rhodium Migration.

The asymmetric rhodium-catalyzed alkenylation of enones and imines with arylboronic acids has been developed. A highly controllable aryl to vinyl 1,4-rhodium migration is the key step. Stereodefined vinyl moieties were installed in excellent enantioselectivies for most examined examples. DFT calculations reveal that the driving force of this rhodium migration is a kinetically favored process.

Effect of Radix isatidis polysaccharide on alleviating insulin resistance in type 2 diabetes mellitus cells and rats.

OBJECTIVES: The objective of this paper was to explore the effects of Radix isatidis polysaccharide (RIP) extracted from Radix isatis on alleviating insulin resistance. METHODS: The insulin resistance models of 3T3-L1 preadipocytes and type 2 diabetic rats were established to evaluate the insulin resistance activity of RIP. KEY FINDINGS: Radix isatidis polysaccharide within the concentration range of 25-100 µg/ml could reduce cell supernatant glucose and TNF-α levels (P < 0.01) and increase the expression of PI-3K P85, Glut4, IRS-1 and Akt protein in symptoms of IR 3T3-L1 preadipocytes. In the meantime, RIP contributed to relieve the weight loss of diabetic rats whose liver weight and liver index were decreased due to the effects of RIP. Experiments in rats also showed that RIP had capacity in reduced serum TC, TG, LDL-C, FFA, FBG, FINS, MDA, ALT, AST activities and increased serum HDL-C, SOD, ISI (P < 0.05 or 0.01). In addition, the oral glucose tolerance in rats was improved (P < 0.05) and liver damage was restored due to RIP. CONCLUSIONS: Radix isatidis polysaccharide significantly alleviates insulin resistance in 3T3-L1 preadipocytes and type 2 diabetic rats. These beneficial effects of RIP may associate with their roles in improving the glucose metabolism, lipid metabolism and oxidative stress.

Highly Stereoselective Synthesis of 1,3-Dienes through an Aryl to Vinyl 1,4-Palladium Migration/Heck Sequence.

An efficient aryl to vinyl 1,4-palladium migration/Heck sequence was developed for the stereoselective synthesis of 1,3-dienes. High stereoselectivity was observed not only for 1,3-dienes bearing two similar aryl groups at terminal positions, but also for those with configurations shown to be unfavorable with previous methods.

Borylation of Olefin C-H Bond via Aryl to Vinyl Palladium 1,4-Migration.

The aryl to vinyl palladium 1,4-migration was realized for the first time. The generated alkenyl palladium species was trapped by diboron reagents under Miyaura borylation conditions, providing a new method to synthesize ß,ß-disubstituted vinylboronates. The excellent regioselectivity and broad substrate scope were observed for this novel transformation.

Synthesis of chiral cyclobutanes via rhodium/diene-catalyzed asymmetric 1,4-addition: a dramatic ligand effect on the diastereoselectivity.

A highly diastereo- and enantioselective rhodium-catalyzed arylation of cyclobutenes for the efficient synthesis of chiral cyclobutanes has been developed. Chiral diene ligands exhibited excellent capability for the reaction diastereoselectivity control.

Room-temperature humidity-sensing performance of SiC nanopaper.

Centimeters-long SiC nanowire could be a strong "bridge" between microworld and macroworld due to its unique morphology, excellent chemical stability, and intriguing physical properties. Here we present a novel "paperlike" material-free-standing SiC nanopaper fabricated by acetone-assisted compression of centimeters-long SiC nanowires. The resistance of this new paperlike material linearly increases with increasing environmental relative humidity in a very short time. We suggest that adsorption of water molecules on SiC nanopaper surface led to fast electron transfer between SiC nanopaper and water layer, which indicates that SiC nanopaper could be applied to high-performance humidity sensor in harsh environment.