共查询到20条相似文献,搜索用时 15 毫秒
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Holger Braunschweig Prof. Dr. Thomas Herbst Dr. Krzysztof Radacki Dr. Gernot Frenking Prof. Dr. Mehmet Ali Celik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):12099-12106
We report on the hydroboration of 1‐[bis(trimethylsilyl)amino]‐2,3‐diethylborirene ( 3 ) with 9‐borabicyclo[3.3.1]nonane (9‐BBN), which led through ring‐opening to an amino(vinyl)borane. The viscous borane was subsequently converted into a crystalline borate on treatment with MeLi. Both compounds were fully characterized by multinuclear NMR spectroscopy and in case of the latter by single‐crystal X‐ray diffraction analysis. To elucidate the reaction mechanism of the unexpected boron‐carbon bond cleavage, DFT calculations of energy minima and transition states for the hydroboration were carried out. 相似文献
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Mary E. Garner Dr. Stephan Hohloch Prof. Dr. Laurent Maron Prof. Dr. John Arnold 《Angewandte Chemie (International ed. in English)》2016,55(44):13789-13792
Actinide complexes demonstrate unparalleled reactivity towards small molecules. However, utilizing these powerful transformations in a predictable and deliberate manner remains challenging. Therefore, developing actinide systems that not only perform noteworthy chemistry but also demonstrate controllable reactivity is a key goal. We describe a bis(NHC)borate thorium‐bpy complex ( 1 ) that is capable of reductively cleaving the R?NC bond in a series of organic isocyanides. In contrast to most actinide‐mediated bond activations, the dealkylation event mediated by 1 is remarkably general and yields very well‐defined products that assist in mechanistic elucidation. Synthesis of the rearranged but‐3‐enyl product from the reaction of 1 and cyclopropylmethyl isocyanide supports the notion of a radical‐based mechanism. 相似文献
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Zuo Hang Yu Christopher J. Reinhardt Thomas Hin-Fung Wong Ka Yan Tong Prof. Jefferson Chan Dr. Ho Yu Au-Yeung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(40):8794-8800
Ascorbate is an important biological reductant and enzyme cofactor. Although direct detection through ascorbate-mediated reduction is possible, this approach suffers from poor selectivity due to the wide range of cellular reducing agents. To overcome this limitation, we leverage reduction potential of ascorbate to mediate a copper-mediated oxidative bond cleavage of ether-caged fluorophores. The copper(II) complexes supported by a {bis(2-pyridylmethyl)}benzylamine or a {bis(2-pyridylmethyl)}(2-methoxybenzyl)amine ligand were identified as an ascorbate responsive unit and their reaction with ascorbate yields a copper-based oxidant that enables rapid benzylic oxidation and the release of an ether-caged dye (coumarin or fluorescein). The copper-mediated bond cleavage is specific to ascorbate and the trigger can be readily derivatized for tuning photophysical properties of the probes. The probes were successfully applied for the fluorometric detection of ascorbate in commercial food samples, human plasma, and serum, and within live cells by using confocal microscopy and flow cytometry. 相似文献
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Gil Cohn David Starosvetsky Rika Hagiwara Digby D. Macdonald Yair Ein-Eli 《Electrochemistry communications》2009,11(10):1916-1918
A new “metal”–air battery based on silicon–oxygen couple is described. Silicon–air battery employing EMI·2.3HF·F room temperature ionic liquid (RTIL) as an electrolyte and highly-doped silicon wafers as anodes (fuels) has an undetectable self-discharge rate and high tolerance to the environment (extreme moisture/dry conditions). Such a battery yields an effectively infinite shelf life with an average working voltage of 1–1.2 V. Silicon–air battery can support relatively high current densities (up to 0.3 mA/cm2) drawn from flat polished silicon wafers anodes. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self sustained energy source. 相似文献
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Selective Carbon–Carbon Bond Cleavage for the Stereoselective Synthesis of Acyclic Systems 下载免费PDF全文
Prof. Dr. Ilan Marek Dr. Ahmad Masarwa Dr. Pierre‐Olivier Delaye Dr. Markus Leibeling 《Angewandte Chemie (International ed. in English)》2015,54(2):414-429
Most of the efforts of organic chemists have been directed to the development of creative strategies to build carbon–carbon and carbon–heteroatom bonds in a predictable and efficient manner. In this Review, we show an alternative approach where challenging molecular skeletons could be prepared through selective cleavage of carbon–carbon bonds. We demonstrate that it has the potential to be a general principle in organic synthesis for the regio‐, diastereo‐, and even enantioselective preparation of adducts despite the fact that C? C single bonds are among the least reactive functional groups. The development of such strategies may have an impact on synthesis design and can ultimately lead to new selective and efficient processes for the utilization of simple hydrocarbons. 相似文献
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Volker Stanjek Martin Miksch Patricia Lueer Ulrich Matern Wilhelm Boland 《Angewandte Chemie (International ed. in English)》1999,38(3):400-402
In contrast to the stepwise oxidative dealkylation of steroids [Eq. (1)], (+)‐marmesin ( 1 ) is directly converted by the psoralen synthase (a cytochrome P450) into the phototoxic furanocoumarin psoralen ( 2 ) and acetone. The dealkylation proceeds as a syn elimination. 相似文献
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Kinetic Resolution of Allyl Fluorides by Enantioselective Allylic Trifluoromethylation Based on Silicon‐Assisted CF Bond Cleavage 下载免费PDF全文
Takayuki Nishimine Kazunobu Fukushi Naoyuki Shibata Hiromi Taira Etsuko Tokunaga Akihito Yamano Dr. Motoo Shiro Prof. Dr. Norio Shibata 《Angewandte Chemie (International ed. in English)》2014,53(2):517-520
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Silicon–Oxygen Double Bonds: A Stable Silanone with a Trigonal‐Planar Coordinated Silicon Center 下载免费PDF全文
Prof. Dr. Alexander C. Filippou Dipl.‐Chem. Bernhard Baars Dr. Oleg Chernov Dipl.‐Chem. Yury N. Lebedev Dr. Gregor Schnakenburg 《Angewandte Chemie (International ed. in English)》2014,53(2):565-570
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Iridium‐Catalyzed Reductive Carbon–Carbon Bond Cleavage Reaction on a Curved Pyridylcorannulene Skeleton 下载免费PDF全文
Dr. Shohei Tashiro Dr. Mihoko Yamada Prof. Dr. Mitsuhiko Shionoya 《Angewandte Chemie (International ed. in English)》2015,54(18):5351-5354
The cleavage of C? C bonds in π‐conjugated systems is an important method for controlling their shape and coplanarity. An efficient way for the cleavage of an aromatic C? C bond in a typical buckybowl corannulene skeleton is reported. The reaction of 2‐pyridylcorannulene with a catalytic amount of IrCl3?n H2O in ethylene glycol at 250 °C resulted in a structural transformation from the curved corannulene skeleton to a strain‐free flat benzo[ghi]fluoranthene skeleton through a site‐selective C? C cleavage reaction. This cleavage reaction was found to be driven by both the coordination of the 2‐pyridyl substituent to iridium and the relief of strain in the curved corannulene skeleton. This finding should facilitate the design of carbon nanomaterials based on C? C bond cleavage reactions. 相似文献
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采用TBHP作为氧化剂,发展了钯催化芳基偶氮化合物N=N双键断裂的氧化羰基化反应.芳基偶氮的羰基化反应在Pd(OAc)2(5%),MeO-BIPHEP (5%),芳基偶氮(0.2 mmol),TBHP(2 equiv),H2O(1 equiv),DCE(1 mL),CO (3.0 MPa)的条件下110℃反应12h后,经柱层析纯化分离得到31%-91%的芳基脲.初步的机理研究表明,芳基偶氮化合物的N=N双键断裂原位产生芳基胺,再进一步氧化羰基化生成芳基脲. 相似文献
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Dr. Youwei Xu Shanmeng Lin Dr. Rongkun He Dr. Yichuan Zhang Dr. Quan Gao Prof. Dennis K. P. Ng Prof. Jin Geng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(44):11268-11272
Photocages for protection and the controlled release of bioactive compounds have been widely investigated. However, the vast majority of these photocages employ the cleavage of single bonds and high-energy ultraviolet light. The construction of a photoactivation system that uses visible light to cleave unsaturated bonds still remains a challenge. Herein, we report a regioselective oxidative cleavage of C=C bonds from a boron-dipyrrolemethene (BODIPY)-based photocage by illumination at 630 nm, resulting in a free aldehyde and a thiol fluorescent probe. This strategy was demonstrated in live HeLa cells, and the generated α-formyl-BODIPY allowed real-time monitoring of aldehyde release in the cells. In particular, it is shown that a mannose-functionalized photocage can target HepG2 cells. 相似文献
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