During the past few decades, there has been considerable growth in the development of denitrogenative reactions of triazole skeletons to construct valuable cyclic compounds, particularly ...heterocycles. Despite the inherent difficulty of the ring‐opening of triazole derivatives, many novel and efficient approaches have arisen in this area mainly with the use of transition metal (such as rhodium, palladium, silver, copper) catalysis, photolysis, or free radical mediated reactions. Generally, these procedures begin with the ring‐opening of 1,2,3‐triazoles or benzotriazoles followed by N2 extrusion and subsequent diverse transformations, which enable the rapid synthesis of various heterocycles in a single step. To avoid overlap with other related reviews, this minireview covers the recent advances in the denitrogenative cyclization of 1,2,3‐triazoles since 2016 and the denitrogenative cyclization of benzotriazoles since 2012.
Open source: Denitrogenation is a very powerful ring‐opening strategy for triazole rings and attracts considerable attention from the organic synthetic community. The reactions of different types of triazoles and benzotriazoles as the precursors for generating carbene or diazonium species provide access to diverse synthetically valuable heterocycles. An overview of the denitrogenative cyclization reaction of triazoles and benzotriazoles is presented.
Despite reducing environmental pollution and the excessive consumption of fossil fuels, the number of battery electric vehicles (BEVs) on the road is still low. Why is this so? Why is the mass ...adoption of BEVs so difficult to realize? One important reason is that the adoption of BEVs is, to a large extent, dependent on the acceptance of private consumers, and their willingness to adopt this mode of transport is insufficient. This study is a systematic overview of peer-reviewed journal articles to identify the reasons for and against consumer intentions to adopt BEVs. A total of 1846 papers were retrieved and after a two-step identification, 40 papers were finally identified and analyzed in detail. The influencing factors were categorized into three main types, namely demographic, situational and psychological, and they were reviewed separately. In addition, the shortcomings and deficiencies in the current studies were also noted.
Gold‐Catalyzed Enantioselective Annulations Li, Yangyan; Li, Wenbo; Zhang, Junliang
Chemistry : a European journal,
January 12, 2017, Letnik:
23, Številka:
3
Journal Article
Recenzirano
In the past decade, there have been many extraordinary advances in the development of gold‐catalyzed enantioselective annulations, such as cycloadditions, cyclizations, cycloisomerizations, and ...tandem annulations, which are of particular interest owing to their potential for rapid construction of optically active hetero‐ and carbocyclic molecules. This Review summarizes the methods to construct chiral cyclic compounds by gold‐catalyzed enantioselective annulations reported since 2005. The Review is organized according to the general annulation types catalyzed by chiral gold complexes or chiral gold salts, which have four main types (cycloadditions, cyclizations of C−C multiple bonds with tethered nucleophiles, cycloisomerization or cyclization of enynes, and tandem annulations), as well as some other strategies. The general reaction mechanisms of each subcategory, key intermediates for some unusual transformations, and the application of several novel ligands and chiral gold salts are also discussed.
Good as gold: Methods to construct chiral cyclic compounds by gold‐catalyzed enantioselective annulations reported since 2005 are summarized, including discussion of four main types of annulation (cycloadditions, cyclizations of C−C multiple bonds with tethered nucleophiles, cycloisomerization or cyclization of enynes, and tandem annulations).
Networks of regulatory enhancers dictate distinct cell identities and cellular responses to diverse signals by instructing precise spatiotemporal patterns of gene expression. However, 35 years after ...their discovery, enhancer functions and mechanisms remain incompletely understood. Intriguingly, recent evidence suggests that many, if not all, functional enhancers are themselves transcription units, generating non-coding enhancer RNAs. This observation provides a fundamental insight into the inter-regulation between enhancers and promoters, which can both act as transcription units; it also raises crucial questions regarding the potential biological roles of the enhancer transcription process and non-coding enhancer RNAs. Here, we review research progress in this field and discuss several important, unresolved questions regarding the roles and mechanisms of enhancers in gene regulation.
The development of transition-metal-catalyzed methods for the synthesis of P-chiral phosphine derivatives poses a considerable challenge. Herein, we present a direct Pd/Xiao-Phos-catalyzed ...cross-coupling reaction of easily accessible secondary phosphine oxides and aryl bromides, which provides rapid access to P-chiral phosphine oxides. The reaction proceeds efficiently with a wide array of reaction partners to deliver various tertiary phosphine oxides in up to 96% yield and 97% ee. Moreover, the synthesis of DiPAMP ligand and its analogues was also realized, which demonstrates a suitable pathway to switching the branched chain of DiPAMP.
The study of the cancer–immune system is important for understanding tumorigenesis and the development of cancer and immunotherapy. In this work, we build a comprehensive cancer–immune model ...including both cells and cytokines to uncover the underlying mechanism of cancer immunity based on landscape topography. We quantify three steady-state attractors, normal state, low cancer state and high cancer state, for the innate immunity and adaptive immunity of cancer. We also illustrate the cardinal inhibiting cancer immunity interactions and promoting cancer immunity interactions through global sensitivity analysis. We simulate tumorigenesis and the development of cancer and classify these into six stages. The characteristics of the six stages can be classified further into three groups. These correspond to the escape, elimination and equilibrium phases in immunoediting, respectively. Under specific cell–cell interactions strength oscillations emerge. We found that tumorigenesis and cancer recovery processes may need to go through cancer–immune oscillation, which consumes more energy. Based on the cancer–immune landscape, we predict three types of cells and two types of cytokines for cancer immunotherapy as well as combination immunotherapy. This landscape framework provides a quantitative way to understand the underlying mechanisms of the interplay between cancer and the immune system for cancer tumorigenesis and development.
For unimodal random variable S with fixed moments
and mode m, a formula on variance of any functions of S is provided along the line of Khintchine transform. Upper bounds are derived on the variance ...of European call options and Gap options. The techniques are based on symmetrization, domination by quadratic functions of two variables and change of measures.
Histone deacetylase inhibitors (HDIs) are a class of prominent epigenetic drugs that are currently being tested in hundreds of clinical trials against a variety of diseases. A few compounds have ...already been approved for treating lymphoma or myeloma. HDIs bind to the zinc-containing catalytic domain of the histone deacetylase (HDACs) and they repress the deacetylase enzymatic activity. The broad therapeutic effect of HDIs with seemingly low toxicity is somewhat puzzling when considering that most HDIs lack strict specificity toward any individual HDAC and, even if they do, each individual HDAC has diverse functions under different physiology scenarios. Here, we review recent mechanistic studies using omics approaches, including epigenomics, transcriptomics, proteomics, metabolomics, and chemoproteomics, methods. These omics studies provide non-biased insights into the mechanism of action for HDIs.
The Chinese government has issued numerous policies to promote the development and adoption of new energy vehicles (NEVs) to address the problem of excessive energy consumption and environmental ...pollution. In this study we divided these policies into seven categories: macroscopic, demonstration, subsidization, preferential tax, technical support, industry management, and infrastructure. Since consumers’ opinions affect the policy choices of government, based on questionnaire data we use a four paradigm model to analyze the consumers’ evaluation of each policy in terms of perceptions of importance and satisfaction. The results show that macroscopic policies are perceived to be of high importance and satisfaction, whereas for industry management policies they are perceived to be of low importance and satisfaction. The importance perceptions of preferential tax and demonstration policies are low, whereas perceptions of their satisfaction are high. Perceptions of the importance of subsidization, technical support, and infrastructure policies are high, whereas perceptions of their satisfaction are low. We find that the subsidization, technical support, and infrastructure policies need urgent improvement. Finally, we put forward several suggestions to improve the current policies and increase the consumers’ intention to adopt NEVs.
•This study divided Chinese NEV-related policies into seven types.•This study analyzed consumers’ evaluation of NEV-related policies.•Consumers’ evaluations about NEV-related policies were diverse.•Subsidization, technical support, and infrastructure policies need improvement.
Sulfur and chlorine are the two most important ligands accounting for metal transport in the upper crust. In this study, four metal- and sulfur-saturated model fluids with varying salinities and ...redox states were simulated in the Fe-Cu-Pb-Zn-Au-S-C-H-O system, over a wide pressure-temperature (P-T) range (50–650°C, 0.8–5.0kbar), in order to compare the roles of chloride and bisulfide complexing for metal transport at the light of the latest available thermodynamic properties. The range in simulated Zn and Pb concentrations of the model fluids compares well with those of natural hydrothermal fluids, suggesting that the model can be used to evaluate hydrothermal ore-forming processes in Nature.
The modeling reveals two different modes of Cu, Pb and Zn complexing in sulfur-saturated hydrothermal solutions. At lower temperature, chloride complexes are the predominant Cu, Pb and Zn species in sulfide-saturated systems, as expected from previous studies. However, hydrosulfide Cu, Pb and Zn complexes predominate at higher temperature. The predominance of bisulfide complexing for base metals at high temperature in sulfur-saturated systems is related to the prograde dissolution of pyrite and/or pyrrhotite, which results in a rapid increase in sulfur solubility.
Metals transport as chloride or bisulfide complexes determines the modes of metal enrichment. In chloride-complexing dominated systems (e.g., Mississipi Valley Type deposits), low sulfide solubilities mean that the ore fluids cannot carry both reduced sulfur and metals, and ore precipitation is triggered when the ore fluid encounters reduced sulfur, e.g., via fluid mixing or via sulfate reduction. In contrast, in fluids where bisulfide complexing is predominant, cooling and desulfidation reactions are efficient mechanisms for base metal sulfide precipitation. Since both Au and base metals (Cu, Pb and Zn) are predicted to be transported as hydrosulfide complexes in high-temperature primary magmatic fluids in equilibrium with sulfide minerals, high-salinity is not a necessity for magmatic hydrothermal deposits such as porphyry- and skarn-style deposits.
•Metal complexing is coupled with the prograde dissolution of Fe-sulfides.•At lower temperature, chloride complexes are the predominant Cu, Pb and Zn species.•Hydrosulfide Cu, Pb and Zn complexes predominate at higher temperature.•Hydrosulfide complexes are predicted to be predominant in primary magmatic fluids.
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