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991.
Lingheng Kong Xi Han Song Liu Yun Zou Yu Lan Xingwei Li 《Angewandte Chemie (International ed. in English)》2020,59(18):7188-7192
Axial‐to‐central chirality transfer is an important strategy to construct chiral centers, where the axially chiral reagents are mostly limited to atropomerically stable ones. Reported herein is a RhIII‐catalyzed enantioselective spiroannulative synthesis of nitrones. The coupling proceeds via C?H arylation to give an atropomerically metastable biaryl, followed by intramolecular dearomative trapping under oxidative conditions with high degree of chirality transfer. 相似文献
992.
Xianhai Tian Lina Song A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2020,59(30):12342-12346
While direct nitrene insertions into C?H bonds have become an important tool for building C?N bonds in modern organic chemistry, the generation of nitrene intermediates always requires transition metals, high temperatures, ultraviolet or laser light. We report a mild synthesis of carbazoles and related building blocks through a visible light‐induced intramolecular C?H amination reaction. A striking advantage of this new method is the use of more reactive aryl sulfilimines instead of the corresponding hazardous azides. Different catalysts and divergent light sources were tested. The reaction scope is broad and the product yield is generally high. An efficient gram‐scale synthesis of Clausine C demonstrates the applicability and scalability of this new method. 相似文献
993.
Wufeng Chen Haibin Song Jianfeng Li Chunming Cui 《Angewandte Chemie (International ed. in English)》2020,59(6):2365-2369
Hydrosilylation of alkynes generally yield vinylsilanes, which are inert to the further hydrosilylation because of the steric effects. Reported here is the first successful dihydrosilylation of aryl‐ and silyl‐substituted internal alkynes enabled by a rare‐earth ate complex to yield geminal bis‐ and tris(silanes), respectively. The lanthanum bis(amido) ate complex supported by an ene‐diamido ligand proved to be the ideal catalyst for this unprecedented transformation, while the same series of yttrium and samarium alkyl and samarium bis(amido) ate complexes exhibited poor activity and selectivity, indicating significant effects of the ionic size and ate structure of the rare‐earth catalysts. 相似文献
994.
Yue Wang Jie Tang Yannan Yang Hao Song Jianye Fu Zhengying Gu Chengzhong Yu 《Angewandte Chemie (International ed. in English)》2020,59(7):2695-2699
Effective messenger RNA (mRNA) transfection in hard‐to‐transfect cells delivered by vectors is a long‐standing challenge. Now it is hypothesized that the high intracellular glutathione level is associated with suppressed mRNA translation. This theory leads to a new design principle of next‐generation mRNA vectors: nanoparticles with glutathione depletion chemistry upregulate mRNA translation and enhance transfection, which is beneficial for mRNA delivery in hard‐to‐transfect cells in vitro and in vivo. 相似文献
995.
Jun‐Chao Liu Wei‐Qiang Liao Peng‐Fei Li Yuan‐Yuan Tang Xiao‐Gang Chen Xian‐Jiang Song Han‐Yue Zhang Yi Zhang Yu‐Meng You Ren‐Gen Xiong 《Angewandte Chemie (International ed. in English)》2020,59(9):3495-3499
Molecular ferroelectrics have attracted considerable interests because of their easy and environmentally friendly processing, low acoustical impedance and mechanical flexibility. Herein, a molecular thermochromic ferroelectric, N,N′‐dimethyl‐1,4‐diazoniabicyclo[2.2.2]octonium tetrachlorocuprate(II) ([DMe‐DABCO]CuCl4) is reported, which shows both excellent ferroelectricity and intriguing thermochromism. [DMe‐DABCO]CuCl4 undergoes a ferroelectric phase transition from Pca21 to Pbcm at a significantly high Curie temperature of 413 K, accompanied by a color change from yellow to red that is due to the remarkable deformation of [CuCl4]2? tetrahedron, where the ferroelectric and paraelectric phases correspond to yellow and red, respectively. Combined with multiple bistable physical properties, [DMe‐DABCO]CuCl4 would be a promising candidate for next‐generation smart devices, and should inspire further exploration of multifunctional molecular ferroelectrics. 相似文献
996.
Qihao Wu Song‐Wei Li Heng Xu Hong Wang Pei Hu Hao Zhang Cheng Luo Kai‐Xian Chen Bastien Nay Yue‐Wei Guo Xu‐Wen Li 《Angewandte Chemie (International ed. in English)》2020,59(29):12105-12112
Placobranchus ocellatus is well known to produce diverse and complex γ‐pyrone polypropionates. In this study, the chemical investigation of P. ocellatus from the South China Sea led to the discovery and identification of ocellatusones A–D, a series of racemic non‐γ‐pyrone polyketides with novel skeletons, characterized by a bicyclo[3.2.1]octane ( 1 , 2 ), a bicyclo[3.3.1]nonane ( 3 ) or a mesitylene‐substituted dimethylfuran‐3(2H)‐one core ( 4 ). Extensive spectroscopic analysis, quantum chemical computation, chemical synthesis, and/or X‐ray diffraction analysis were used to determine the structure and absolute configuration of the new compounds, including each enantiomer of racemic compounds 1 – 4 after chiral HPLC resolution. An array of new and diversity‐generating rearrangements is proposed to explain the biosynthesis of these unusual compounds based on careful structural analysis and comparison with six known co‐occurring γ‐pyrones ( 5 – 10 ). Furthermore, the successful biomimetic semisynthesis of ocellatusone A ( 1 ) confirmed the proposed rearrangement through an unprecedented acid induced cascade reaction. 相似文献
997.
Xuan Zhou Kai Li Yunxiang Lin Li Song Jincheng Liu Yu Liu Lingling Zhang Zhijian Wu Shuyan Song Jun Li Hongjie Zhang 《Angewandte Chemie (International ed. in English)》2020,59(32):13568-13574
Synthesis of well‐defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single‐atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO2 as a carrier and transition‐metal single atoms as an intermediate state. The supported nanoalloys/CeO2 with ultra‐low noble metal content (containing 0.2 wt % Au and 0.2 wt % Pt) exhibit enhanced catalytic performance towards complete CO oxidation at room temperature and remarkable thermostability. This work provides a general strategy for facile and rapid synthesis of well‐defined atomically mixed nanoalloys that can be applied for a range of emerging techniques. 相似文献
998.
Zhantao Peng Bin Di Wentao Li Dan Liu Xiaojie Wen Hao Zhu Huanjun Song Yajie Zhang Cen Yin Xiong Zhou Kai Wu 《Angewandte Chemie (International ed. in English)》2020,59(34):14321-14325
Potassium (K) cations are spontaneously formed upon thermal deposition of low‐coverage K onto an ultrathin CuO monolayer grown on Cu(110) and they were explored by low‐temperature scanning tunneling microscopy (STM) and X‐ray photoemission spectroscopy. The formed K cations are highly immobile and thermally stable. The local work function around an individual K cation decreases by 1.5±0.3 eV, and a charging zone underneath it is established within about 1.0 nm. The cationic and neutral states of the K atom are switchable upon application of an STM bias voltage pulse, which is simultaneously accompanied by an adsorption site relocation. 相似文献
999.
1000.
Xiangyu Ma Yuyuan Bai Yongbo Song Qinzhen Li Ying Lv Hui Zhang Haizhu Yu Manzhou Zhu 《Angewandte Chemie (International ed. in English)》2020,59(39):17234-17238
Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size‐evolution principles. Reported here is the largest known FCC‐based (FCC=face centered cubic) silver nanocluster, [Ag100(SC6H33,4F2)48(PPh3)8]?: the first all‐octahedral symmetric nesting Ag nanocluster with a four‐layered Ag6@Ag38@Ag48S24@Ag8S24P8 structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC‐based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC‐based Russian nesting doll model constitutes a new platform for the study of the size‐evolution principles of Ag NCs. 相似文献