Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross‐coupling of heteroarenes with aliphatic C−H bonds provides straightforward access ...to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross‐coupling of heteroarenes and C(sp3)−H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)−H donor is converted to a nucleophilic carbon radical through H‐atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl−. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products.
An efficient photoelectrochemical dehydrogenative cross‐coupling of heteroarenes with C(sp3)−H species is described. Chlorine atoms, which are produced by light irradiation of anodically generated Cl2 from Cl−, a hydrogen atom from C(sp3)−H bonds to afford carbon radicals. The latter undergo Minisci alkylation to afford the final functionalized heteroarene products.
A photoelectrochemical method for the C−H alkylation of heteroarenes with organotrifluoroborates has been developed. The merger of electrocatalysis and photoredox catalysis provides a chemical ...oxidant‐free approach for the generation and functionalization of alkyl radicals from organotrifluoroborates. A variety of heteroarenes were functionalized using primary, secondary, and tertiary alkyltrifluoroborates with excellent regio‐ and chemoselectivity.
A radical approach: A photoelectrochemical method has been developed for the C−H alkylation of heteroarenes with organotrifluoroborates under oxidant‐free conditions. A variety of heteroarenes can be functionalized with primary, secondary, and tertiary alkyl groups with excellent regio‐ and chemoselectivity.
Organic radicals are versatile synthetic intermediates that provide reactivities and selectivities complementary to ionic species. Despite its long history, electrochemically driven radical reactions ...remain limited in scope. In the past few years, there have been dramatic increase in research activity in organic electrochemistry. We have been developing electrochemical and electrophotocatalytic methods for the generation and synthetic utilization of organic radicals. In our studies, various radical species such as alkene and arene radical cations and carbon‐ and heteroatom‐centered radicals are generated from readily available precursors through direct electrolysis, molecular electrocatalysis or molecular electrophotocatalysis. These radical species undergo various inter‐ and intramolecular oxidative transformations to rapidly increase molecular complexity. The simultaneous occurrence of anodic oxidation and cathodic proton reduction allows the oxidative reactions to proceed through H2 evolution without external chemical oxidants.
Organic radicals are versatile intermediates that provide reactivities and selectivities complementary to ionic species. Herein, we summarize some of our efforts in developing electrochemically driven radical reactions. The organic radical intermediates are generated via direct electrolysis, indirect electrolysis employing a homogeneous molecular catalyst or molecular electrophotocatalysis.
There is a resurgence of interests in organic electrochemistry, which is generally accepted as a green synthetic tool. In this context, many electrochemical methods have been developed in the past ...decade to access various nitrogen-centered radicals (NCRs) from readily available precursors in a controlled fashion, enabling the rapid development of many NCR-mediated new reactions for the construction of nitrogen-containing organic compounds. In this review, recent advances in the chemistry of electrochemically generated NCRs are critically highlighted, based on the electrochemical strategies for their formation and the types of NCRs. Focus is put on the mechanism for the electrochemical generation of different NCRs and their synthetic applications.
Recent advances in the chemistry of electrochemically generated NCRs are critically highlighted with focus on the mechanism for the electrochemical generation of different NCRs and their synthetic applications. Display omitted
Benzimidazolone and benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the ...construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic rings through a dehydrogenative cyclization cascade. Readily available arylamine‐tethered 1,5‐enynes undergo a biscyclization/dehydrogenation cascade to afford functionalized benzanellated heterocycles in a single step with complete control of regioselectivity. These electricity‐powered oxidative transformations proceed with H2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents.
It's electrifying! An electricity‐powered synthesis of highly substituted benzimidazolone and benzoxazolone derivatives is reported, in which de novo construction of the benzene and the heterocyclic ring is achieved through a dehydrogenative cyclization cascade. The electrosynthesis method proceeds with H2 evolution, thus obviating the need for oxidizing reagents and proton acceptors.
Reported herein is an unprecedented synthesis of C3‐fluorinated oxindoles through cross‐dehydrogenative coupling of C(sp3)‐H and C(sp2)‐H bonds from malonate amides. Under the unique and mild ...electrochemical conditions, the requisite oxidant and base are generated in a continuous fashion, allowing the formation of the base‐ and heat‐sensitive 3‐fluorooxindoles in high efficiency with broad substrate scope. The synthetic usefulness of the electrochemical method is further highlighted by its easy scalability and the diverse transformations of the electrolysis product.
C−H functionalization: A ferrocene‐catalyzed electrochemical cross‐coupling reaction of C(sp3)‐H and C(sp2)‐H centers has been developed to give access to C3‐fluorinated oxindoles using fluorinated malonate amides. The electrosynthetic method is characterized by mild reaction conditions, broad substrate scope, high functional group tolerance, and easy scalability.
Decarboxylative C−H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step‐ and atom‐economical features and the pervasiveness of ...carboxylic acids and C−H bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative carbon–carbon bond formation with proton reduction remain an unsolved challenge. Herein, we report an electrophotocatalytic approach that merges organic electrochemistry with photocatalysis to achieve the efficient direct decarboxylative C−H alkylation and carbamoylation of heteroaromatic compounds through hydrogen evolution. This electrophotocatalytic method, which combines the high efficiency and selectivity of photocatalysis in promoting decarboxylation with the superiority of electrochemistry in effecting proton reduction, enables the efficient coupling of a wide range of heteroaromatic bases with a variety of carboxylic acids and oxamic acids. Advantageously, this method is scalable to decagram amounts, and applicable to the late‐stage functionalization of drug molecules.
A broadly applicable electrophotocatalytic method for the direct decarboxylative C−H alkylation and carbamoylation of heteroarenes has been developed. This method combines the advantages of photocatalysis and electrochemistry to enable the functionalization of a broad range of substrates and to allow the decarboxylative C−H functionalization reactions to proceed by H2 evolution, obviating the need for oxidizing reagents and proton acceptors.
Multi-View Intact Space Learning Xu, Chang; Tao, Dacheng; Xu, Chao
IEEE transactions on pattern analysis and machine intelligence,
2015-Dec.-1, 2015-Dec, 2015-12-1, 20151201, Letnik:
37, Številka:
12
Journal Article
Recenzirano
Odprti dostop
It is practical to assume that an individual view is unlikely to be sufficient for effective multi-view learning. Therefore, integration of multi-view information is both valuable and necessary. In ...this paper, we propose the Multi-view Intact Space Learning (MISL) algorithm, which integrates the encoded complementary information in multiple views to discover a latent intact representation of the data. Even though each view on its own is insufficient, we show theoretically that by combing multiple views we can obtain abundant information for latent intact space learning. Employing the Cauchy loss (a technique used in statistical learning) as the error measurement strengthens robustness to outliers. We propose a new definition of multi-view stability and then derive the generalization error bound based on multi-view stability and Rademacher complexity, and show that the complementarity between multiple views is beneficial for the stability and generalization. MISL is efficiently optimized using a novel Iteratively Reweight Residuals (IRR) technique, whose convergence is theoretically analyzed. Experiments on synthetic data and real-world datasets demonstrate that MISL is an effective and promising algorithm for practical applications.
Dehydrogenative annulation reactions are among the most straightforward and efficient approach for the preparation of cyclic structures. However, the applications of this strategy for the synthesis ...of saturated heterocycles have been rare. In addition, reported dehydrogenative bond-forming reactions commonly employ stoichiometric chemical oxidants, the use of which reduces the sustainability of the synthesis and brings safety and environmental issues. Herein, we report an organocatalyzed electrochemical dehydrogenative annulation reaction of alkenes with 1,2- and 1,3-diols for the synthesis of 1,4-dioxane and 1,4-dioxepane derivatives. The combination of electrochemistry and redox catalysis using an organic catalyst allows the electrosynthesis to proceed under transition metal- and oxidizing reagent-free conditions. In addition, the electrolytic method has a broad substrate scope and is compatible with many common functional groups, providing an efficient and straightforward access to functionalized 1,4-dioxane and 1,4-dioxepane products with diverse substitution patterns.
Although clinical studies have shown promise for targeting programmed cell death protein-1 (PD-1) and ligand (PD-L1) signaling in non-small cell lung cancer (NSCLC), the factors that predict which ...subtype patients will be responsive to checkpoint blockade are not fully understood.
We performed an integrated analysis on the multiple-dimensional data types including genomic, transcriptomic, proteomic, and clinical data from cohorts of lung adenocarcinoma public (discovery set) and internal (validation set) database and immunotherapeutic patients. Gene set enrichment analysis (GSEA) was used to determine potentially relevant gene expression signatures between specific subgroups.
We observed that
mutation significantly increased expression of immune checkpoints and activated T-effector and interferon-γ signature. More importantly, the
comutated subgroup manifested exclusive increased expression of PD-L1 and a highest proportion of
Meanwhile,
or
-mutated tumors showed prominently increased mutation burden and specifically enriched in the transversion-high (TH) cohort. Further analysis focused on the potential molecular mechanism revealed that
or
mutation altered a group of genes involved in cell-cycle regulating, DNA replication and damage repair. Finally, immunotherapeutic analysis from public clinical trial and prospective observation in our center were further confirmed that
or
mutation patients, especially those with co-occurring
mutations, showed remarkable clinical benefit to PD-1 inhibitors.
This work provides evidence that
and
mutation in lung adenocarcinoma may be served as a pair of potential predictive factors in guiding anti-PD-1/PD-L1 immunotherapy.
.
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