B(C6F5)3-Catalyzed tandem cyclization/hydrosilylation for the step-economical construction of 1,2,3,4-tetrahydroquinoxalines from readily available starting materials has been developed.

No abstract

A rhodium(III)‐catalyzed direct ortho CH bond olefination of arenes, including but not limited to benzamides, arylpyridines and indoles, with a variety of unactivated aliphatic olefins has been developed. In the presence of catalytic amounts of dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer {[Cp*RhCl2]2}, copper(II) acetate monohydrate [Cu(OAc)2⋅H2O] and silver hexafluoroantimonate(V) (AgSbF6), the coupling reaction occurred efficiently to afford the ortho‐olefinated linear products in good to excellent yields with high regio‐ and stereoselectivities, and a range of functional groups in both coupling partners is compatible with the reaction conditions. This protocol relies on the use of directing groups, and the addition of AgSbF6 as additive is crucial for the catalysis. This new method expands the scope of rhodium(III)‐catalyzed direct CH bond olefination of arenes, and provides a rapid access to useful linear arylation products of unactivated olefins.magnified image

The first B(C 6 F 5 ) 3 -catalyzed deoxygenative reduction of amides into the corresponding amines with readily accessible and stable ammonia borane (AB) as a reducing agent under mild reaction conditions is reported. This metal-free protocol provides facile access to a wide range of structurally diverse amine products in good to excellent yields, and various functional groups including those that are reduction-sensitive were well tolerated. This new method is also applicable to chiral amide substrates without erosion of the enantiomeric purity. The role of BF 3 · OEt 2 co-catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of an amide-boron adduct.

Co(III)-catalyzed highly regio-and stereoselective direct C6 olefination of 2-pyridones with alkynes has been developed with the assistance of chelation. Upon variation of the reaction conditions, 2-pyridones react well with diaryl alkynes via a C6 olefination/directing group migration pathway to give the tetrasubstituted 6-vinyl-2-pyridones, but the C6−H olefination with terminal alkynes works effectively to afford only the C6-olefinated 2-pyridones. A judicious choice of a solvent and an additive is crucial for catalysis. The protocols feature 100% atom economy, excellent site selectivity, high stereoselectivity, an ample substrate scope, and good compatibility of functional groups. Synthetic applications are demonstrated, and experimental studies and density functional theory calculations are conducted to gain mechanistic insight into the two transformations.

An investigation employingt he catalytic systemc onsisting of (pentamethylcyclopentadienyl)rhodiumd ichloride dimer [Cp*RhCl 2 ] 2 and 2,2'-bipyridine (bpy) for transfer hydrogenation of av ariety of quinoxalines,q uinoxalinones,q uinolines andi ndoles under aqueous conditions with formate as the hydrogen source is reported. This approach providesv arious tetrahydroquinoxalines,d ihydroquinoxalinones, tetrahydroquinolines andi ndolinesi ng ood to excellent yields.T he activity of the catalyst towards quinoxalines and quinoxalinones is excellent, with asubstrate to catalyst ratio (S/C) of 10000 being feasible. Thec hoice of ligand is critical to the catalysis,a nd the aqueous phase reductioni ss hownt ob eh ighly pH-dependent, with acidic pH values needed for optimal reduction. Thec atalyst is easy to access,a nd the reactioniso perationally simple without requiring an inert atmosphere.

Oxidative stress and excessive inflammatory responses are the two critical mechanisms of hepatic ischemia-reperfusion injury (HIRI) encountered in many clinical settings, including following hepatectomy and liver transplantation. Effective anti-inflammatory and anti-oxidative pharmacological interventions are urgently needed to counter HIRI. The present study showed that a biocompatible Prussian blue (PB) scavenger with reactive oxygen species (ROS) scavenging and anti-inflammatory properties might be used a promising treatment for HIRI. Following intravenous administration, PB scavenger was mainly distributed in the liver, where it showed excellent ability to alleviate apoptosis, tissue injury and organ dysfunction after HIRI. PB scavenger was found to protect liver tissue by scavenging ROS, reducing neutrophil infiltration and promoting macrophage M2 polarization. In addition, PB scavenger significantly reduced oxidative stress in primary hepatocytes, restoring cell viability under oxidative stress condition. PB scavenger effectively reduced lipopolysaccharide-stimulated inflammation in RAW 264.7 cells. These findings indicate that PB scavenger may be a potential therapeutic agent for the treatment of HIRI, providing an alternative treatment for ROS-associated and inflammatory liver diseases.

A general and efficient Rh(I)-catalyzed decarbonylative direct C2-olefination of indoles with vinyl carboxylic acids has been developed. The reaction exhibits excellent functional group tolerance, regioselectivity and stereoselectivity, giving a broad range of C2-alkenylated indoles in good to excellent yields.