Search

Visible-light photocatalysis has evolved as a powerful technique to enable controllable radical reactions. Exploring unique photocatalytic mode for obtaining new chemoselectivity and product diversity is of great significance. Herein, we present a photo-induced chemoselective 1,2-diheteroarylation of unactivated alkenes utilizing halopyridines and quinolines. The ring-fused azaarenes serve as not only substrate, but also potential precursors for halogen-atom abstraction for pyridyl radical generation in this photocatalysis. As a complement to metal catalysis, this photo-induced radical process with mild and redox neutral conditions assembles two different heteroaryl groups into alkenes regioselectively and contribute to broad substrates scope. The obtained products containing aza-arene units permit various further diversifications, demonstrating the synthetic utility of this protocol. We anticipate that this protocol will trigger the further advancement of photo-induced alkyl/aryl halides activation. Visible-light photocatalysis has evolved as a powerful technique to enable controllable radical reactions and the exploration of new photocatalytic mode for product diversity is of great significance. Herein, the authors present a photo-induced chemoselective 1,2-diheteroarylation of unactivated alkenes utilizing halopyridines and quinolines. [ABSTRACT FROM AUTHOR]

The construction of multiple continuous fully substituted carbon centers, which serve as unique structural motif in natural products, is a challenging topic in organic synthesis. Herein, we report a hydrated [3+2] cyclotelomerization of butafulvenes to create contiguous fully substituted carbon backbone. In the presence of scandium triflate, all‐carbon skeleton with spiro fused tricyclic ring can be constructed in high diastereoselectivity by utilizing butafulvene as the synthon. Mechanistic studies suggest that this atom‐economic reaction probably proceeds through a synergistic process containing butafulvenes dimerization and nucleophilic attack by water. In addition, the tricyclic product can undergo a series of synthetic derivatizations, which highlights the potential applications of this strategy. The recyclability of Sc(OTf)3 has also been demonstrated to show its robust performance in this hydrated cyclotelomerization. [ABSTRACT FROM AUTHOR]

Bridged benzazepine scaffolds, possessing unique structural and physicochemical activities, are widespread in various natural products and drugs. The construction of these skeletons often requires elaborate synthetic effort with low efficiency. Herein, we develop a simple and divergent approach for constructing various bridged benzazepines by a photocatalytic intermolecular dearomatization of naphthalene derivatives with readily available α‐amino acids. The bridged motif is created via a cascade sequence involving photocatalytic 1,4‐hydroaminoalkylation, alkene isomerization and cyclization. Interestingly, the diastereoselectivity can be regulated through different reaction modes in the cyclization step. Moreover, aminohydroxylation and its further bromination have also been demonstrated to access highly functionalized bridged benzazepines. Preliminary mechanistic studies have been performed to get insights into the mechanism. This method provides a divergent synthetic approach for construction of highly functionalized bridged benzazepines, which have been otherwise difficult to access. [ABSTRACT FROM AUTHOR]

Phthalimide derivatives are prevalent in a wide array of biologically important molecules, including drugs, fungicides, and anticancer molecules. Thus, catalytic methods that directly edit the phthalimide moiety, in particular, decarbonylation and derivatization, could be strategically valuable for the modification of existing phthalimide molecular scaffolds. In recent years, considerable efforts have been devoted to emulating the transition-metal-catalyzed phthalimide decarbonylative reaction. A set of elegant strategies, including decarbonylative addition reactions with alkynes, alkenes, and benzynes, decarbonylative polymerization, alkylation, arylation, and protodecarbonylation, have been demonstrated. This review aims to highlight these advances and discusses the mechanism issues, to further expand application and promote developments in this field. 1 Introduction 2 Decarbonylative Addition Reaction with Alkynes 3 Decarbonylative Addition Reaction with Alkenes 4 Decarbonylative Addition Reaction with Benzyne 5 Decarbonylative Polymerization 6 Decarbonylative Alkylation 7 Decarbonylative Arylation 8 Protodecarbonylation 9 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Amides have played a vital role in polymeric materials, natural products and pharmaceuticals. In recent years, transition metal catalyzed C−N bond formation reaction provides a reliable strategy for amides construction. Herein, we disclosed a photo‐induced electrophilic amidation reaction with N‐methoxyamides and arylboronic acids at low temperature using a simple iron salt as the catalyst precursor. Initial mechanistic studies suggested that crucial amide radical species was involved. [ABSTRACT FROM AUTHOR]

Diaryl 1,3,5‐triazines are not only important linkers in various covalent‐ and metal‐organic frameworks but also versatile electron acceptors in host materials for organic light‐emitting diodes (OLEDs). We herein report C−H acetoxylation, benzoxylation, methoxylation, and halogenation of a diverse array of diaryl 1,3,5‐triazines under palladium catalysis. Both symmetrical and nonsymmetrical diaryltriazines are viable substrates. This work offers a potential alternative to the existing methods in preparation or modification of functional materials.Diaryltriazines are widely distributed in functional materials such as MOFs, COFs, and OLEDs. Herein, a catalytic C−H activation strategy is developed to install diverse functional groups including acetoxy, benzoxy, methoxy, chloro, and bromo into diaryltriazines. This protocol might have potential applications for the preparation and modification of those functional materials. [ABSTRACT FROM AUTHOR]

Ynamides are unique alkynes with a carbon–carbon triple bond directly attached to the nitrogen atom bearing an electron-withdrawing group. The alkyne is strongly polarized by the electron-donating nitrogen atom, but its high reactivity can be finely tempered by the electron-withdrawing group. Accordingly, ynamides are endowed with both nucleophilic and electrophilic properties and their chemistry has been an active research field. The catalytic intermolecular annulations of ynamides, featuring divergent assembly of structurally important amino-heterocycles in a regioselective manner, have gained much attention over the past decade. This review aims to provide a comprehensive summary of the advances achieved in this area involving transition metal and acid catalysis. Moreover, the intermolecular annulations of ynamide analogs including ynol ethers and thioalkynes are also discussed, which can provide insights into the reactivity difference caused by the heteroatoms. [ABSTRACT FROM AUTHOR]

Transition metal catalyzed decarbonylation offers a distinct synthetic strategy for new chemical bond formation. However, the π‐backbonding between CO π* orbitals and metal center d‐orbitals impedes ligand dissociation to regenerate the catalyst under mild reaction conditions. Developed here is visible light induced rhodium catalysis for decarbonylative coupling of imides with alkynes under ambient conditions. Initial mechanistic studies suggest that the rhodium complex simultaneously serves as the catalytic center and photosensitizer for decarbonylation. This visible light promoted catalytic decarbonylation strategy offers new opportunities for reviewing old transformations with ligand dissociation as a rate‐determining step. [ABSTRACT FROM AUTHOR]

A ruthenium-catalyzed allylic C(sp3)–H activation strategy has been employed to develop an intermolecular coupling of alkenyl sulfonamides with alkynes. This protocol features the diastereoselective construction of [3.3.0] and [4.3.0] bicyclic sultams in one step. [ABSTRACT FROM AUTHOR]

Abstract Background HOXB9 is a homeobox transcription factor which plays an important role in carcinoma development. This protein has been shown to inhibit cancer cell proliferation. However, the mechanisms that underpin HOXB9-mediated inhibition of cellular proliferation remain to be elucidated. Methods In this study, two gastric cancer cell lines, SGC7901 and MKN45, were transfected with plasmids pLVX-HOXB9 and shHOXB9. These transfections resulted in the over-expression of the HOXB9 gene in the SGC7901/HOXB9 cells and knockdown of the HOXB9 gene in the MKN45/shHOXB9 cells. Results Over-expression of the HOXB9 gene in the SGC7901/HOXB9 cells caused an increase in the apoptotic rate and a concomitant reduction in metastatic ability compared with the knocked-down MKN45/shHOXB9 cells. Moreover, a reduction in the expression of the phosphorylated-Akt protein was observed in the SGC7901/HOXB9 cells, while an increase in expression of the same protein was observed in the MKN45/shHOXB9 cells. We also observed that HOXB9 mediated a reduction in both NF-κB and N-cadherin and Snail protein expression. Conversely, HOXB9 caused an increase in the expression of E-cadherin. Conclusions In summary, this study reports that HOXB9 can suppress both phosphorylated-Akt expression and NF-κB activity. The latter phenomenon affects Snail protein expression and the inhibition of gastric carcinoma proliferation. [ABSTRACT FROM AUTHOR]

RhIII‐ and IrIII‐catalyzed asymmetric C−H functionalization reactions of arenes have relied on the employment of chiral RhIII/IrIII cyclopentadienyl catalysts, the introduction of chiral carboxylic acids to achiral Cp*RhX2 catalysts, and the integration of both strategies. Despite considerable progress, each reaction only provided a specific configuration of the enantioenriched product when using a particular chiral catalyst. Reported in this work is the enantiodivergent coupling of sulfoximines with various diazo compounds by RhIII‐catalyzed desymmetrizing annulation. The enantiodivergence was enabled by a judicious choice of achiral carboxylic acids, and the enantioselectivity correlates with the steric bias of the carboxylic acid and the sulfoximine. [ABSTRACT FROM AUTHOR]