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71.
Rhodium(III)-catalyzed [4 + 1] cyclization of azobenzenes with α-Cl ketones has been developed. 3-Acyl-2H-indazoles could be easily afforded in up to 97% yields for more than 30 examples. The obtained products are potentially valuable in organic synthesis and drug discovery. This protocol featured with high efficiency, extensive functional group tolerance and mild reaction conditions. The one-step efficient construction of an anti-inflammatory agent confirms the practicability of this procedure. 相似文献
72.
73.
Zi‐Yu Li Zhen Yuan Dr. Yan‐Xia Zhao Prof. Dr. Sheng‐Gui He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):4163-4169
Metal carbide species have been proposed as a new type of chemical entity to activate methane in both gas‐phase and condensed‐phase studies. Herein, methane activation by the diatomic cation MoC+ is presented. MoC+ ions have been prepared and mass‐selected by a quadrupole mass filter and then allowed to interact with methane in a hexapole reaction cell. The reactant and product ions have been detected by a reflectron time‐of‐flight mass spectrometer. Bare metal Mo+ and MoC2H2+ ions have been observed as products, suggesting the occurrence of ethylene elimination and dehydrogenation reactions. The branching ratio of the C2H4 elimination channel is much larger than that of the dehydrogenation channel. Density functional theory calculations have been performed to explore in detail the mechanism of the reaction of MoC+ with CH4. The computed results indicate that the ethylene elimination process involves the occurrence of spin conversions in the C?C coupling (doublet→quartet) and hydrogen atom transfer (quartet→sextet) steps. The carbon atom in MoC+ plays a key role in methane activation because it becomes sp3 hybridized in the initial stages of the ethylene elimination reaction, which leads to much lower energy barriers and more stable intermediates. This study provides insights into the C?H bond activation and C?C coupling involved in methane transformation over molybdenum carbide‐based catalysts. 相似文献
74.
Metal‐Free Oxidative Radical Addition of Carbonyl Compounds to α,α‐Diaryl Allylic Alcohols: Synthesis of Highly Functionalized Ketones
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Xue‐Qiang Chu Hua Meng You Zi Prof. Dr. Xiao‐Ping Xu Prof. Dr. Shun‐Jun Ji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17198-17206
A metal‐free direct alkylation of simple carbonyl compounds (ketones, esters, and amides) with α,α‐diaryl allylic alcohols is described. The protocol provides facile access to highly functionalized dicarbonyl ketones by a radical addition/1,2‐aryl migration cascade. The regioselectivity of the reaction was precisely controlled by the nature of the carbonyl compound. 相似文献
75.
Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid
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Dr. Dao‐Juan Cheng Liang Yan Prof. Dr. Shi‐Kai Tian Ming‐Yue Wu Lu‐Xin Wang Zi‐Li Fan Dr. Sheng‐Cai Zheng Prof. Dr. Xin‐Yuan Liu Prof. Dr. Bin Tan 《Angewandte Chemie (International ed. in English)》2014,53(14):3684-3687
A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities. 相似文献
76.
Dr. Xiaocui Guo Prof. Feng Li Chunxia Liu Yi Zhu Nannan Xiao Dr. Zi Gu Prof. Dan Luo Prof. Jianhui Jiang Prof. Dayong Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20832-20839
The design of controllable dynamic systems is vital for the construction of organelle-like architectures in living cells, but has proven difficult due to the lack of control over defined topological transformation of self-assembled structures. Herein, we report a DNA based dynamic assembly system that achieves lysosomal acidic microenvironment specifically inducing topological transformation from nanoparticles to organelle-like hydrogel architecture in living cells. Designer DNA nanoparticles are constructed from double-stranded DNA with cytosine-rich stick ends (C-monomer) and are internalized into cells through lysosomal pathway. The lysosomal acidic microenvironment can activate the assembly of DNA monomers, inducing transformation from nanoparticles to micro-sized organelle-like hydrogel which could further escape into cytoplasm. We show how the hydrogel regulates cellular behaviors: cytoskeleton is deformed, cell tentacles are significantly shortened, and cell migration is promoted. 相似文献
77.
Wen-Wen Zi Zihao Gao Prof. Jun Zhang Bao-Xun Zhao Xian-Shu Cai Prof. Hong-Bin Du Prof. Fei-Jian Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3976-3979
Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q4) and unusual three-connected (Q3) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents. 相似文献
78.
Pan Li Shijun Xu Chunyang Yu Zi‐Ying Li Jianping Xu Zi‐Mu Li Lingyi Zou Xuebing Leng Shan Gao Zhiqiang Liu Xiaoyun Liu Shaodong Zhang 《Angewandte Chemie (International ed. in English)》2020,59(18):7113-7121
Considerable efforts have been made to increase the topological complexity of mechanically interlocked molecules over the years. Three‐dimensional catenated structures composed of two or several (usually symmetrical) cages are one representative example. However, owing to the lack of an efficient universal synthetic strategy, interlocked structures made up of dissymmetric cages are relatively rare. Since the space volume of the inner cavity of an interlocked structure is smaller than that outside it, we developed a novel synthetic approach with the voluminous reductant NaBH(OAc)3 that discriminates this space difference, and therefore selectively reduces the outer surface of a catenated dimer composed of two symmetric cages, thus yielding the corresponding catenane with dissymmetric cages. Insight into the template effect that facilitates the catenation of cages was provided by computational and experimental techniques. 相似文献
79.
Van T. Tran Zi‐Qi Li Omar Apolinar Joseph Derosa Matthew V. Joannou Steven R. Wisniewski Martin D. Eastgate Keary M. Engle 《Angewandte Chemie (International ed. in English)》2020,59(19):7409-7413
We report that Ni(COD)(DQ) (COD=1,5‐cyclooctadiene, DQ=duroquinone), an air‐stable 18‐electron complex originally described by Schrauzer in 1962, is a competent precatalyst for a variety of nickel‐catalyzed synthetic methods from the literature. Due to its apparent stability, use of Ni(COD)(DQ) as a precatalyst allows reactions to be conveniently performed without use of an inert‐atmosphere glovebox, as demonstrated across several case studies. 相似文献
80.
Ze‐Fan Yao Zi‐Yuan Wang Hao‐Tian Wu Yang Lu Qi‐Yi Li Lin Zou Jie‐Yu Wang Jian Pei 《Angewandte Chemie (International ed. in English)》2020,59(40):17467-17471
Controlling the solution‐state aggregation of conjugated polymers for producing specific microstructures remains challenging. Herein, a practical approach is developed to finely tune the solid‐state microstructures through temperature‐controlled solution‐state aggregation and polymer crystallization. High temperature generates significant conformation fluctuation of conjugated backbones in solution, which facilitates the polymer crystallization from solvated aggregates to orderly packed structures. The polymer films deposited at high temperatures exhibit less structural disorders and higher electron mobilities (up to two orders of magnitude) in field‐effect transistors, compared to those deposited at low temperatures. This work provides an effective strategy to tune the solution‐state aggregation to reveal the relationship between solution‐state aggregation and solid‐state microstructures of conjugated polymers. 相似文献