نتایج جستجو برای: fluorination

تعداد نتایج: 1361  

2018
Shunsuke Kuribayashi Tomoyuki Kurioka Shinsuke Inagi Ho-Jung Lu Biing-Jiun Uang Toshio Fuchigami

We herein report that the regioselective anodic fluorination of S-alkyl benzothioate and its derivatives in various aprotic solvents using Et3N·nHF (n = 3-5) and Et4NF·nHF (n = 3-5) as supporting electrolyte and a fluorine source successfully provided the corresponding α-fluorinated products in moderate yields. Dichloromethane containing Et4NF·4HF was found to be the most suitable combination a...

Journal: :Physical chemistry chemical physics : PCCP 2012
Jing Zeng Ke-Qiu Chen Chang Q Sun

By applying the nonequilibrium Green's functions and the density-functional theory, we investigate the electronic structures and transport properties of fluorinated zigzag-edged boron nitride nanoribbons. The results show that the transition between half-metal and semiconductor in zigzag-edged boron nitride nanoribbons can be realized by fluorination at different sites or by the change of the f...

2014
Kazutaka Shibatomi Takuya Okimi Yoshiyuki Abe Akira Narayama Nami Nakamura Seiji Iwasa

In a previous study it was shown that the enantioselective α-fluorination of racemic α-chloroaldehydes with a chiral organocatalyst yielded the corresponding α-chloro-α-fluoroaldehydes with high enantioselectivity. It was also revealed that kinetic resolution of the starting aldehydes was involved in this asymmetric fluorination. This paper describes the determination of the absolute stereochem...

Journal: :Beilstein Journal of Organic Chemistry 2007
Marcin Sawicki Angela Kwok Matthew Tredwell Véronique Gouverneur

Acyclic allylic monofluorides were prepared by electrophilic fluorination of branched (E)-allylsilanes with Selectfluor. These reactions proceeded with efficient transfer of chirality from the silylated to the fluorinated stereocentre. Upon double fluorination, an unsymmetrical ethyl syn-2,5-difluoroalk-3-enoic ester was prepared, the silyl group acting as an anti stereodirecting group for the ...

Journal: :Chemical communications 2015
Megan N Stewart Brian G Hockley Peter J H Scott

Green strategies for late-stage fluorination with (18)F, in which ethanol and water are the only solvents used throughout the entire radiolabeling process (azeotropic drying, nucleophilic fluorination, purification and formulation), have been developed and applied to the radiosyntheses of a range of radiopharmaceuticals commonly employed in clinical PET imaging.

Journal: :Chemistry 2014
Ran-Ning Guo Xian-Feng Cai Lei Shi Zhang-Pei Chen Yong-Gui Zhou

An efficient and transition-metal-free approach was developed to access a series of fluorinated heteroaromatics in moderate to excellent yields. This one-pot procedure features a triple-relay transformation of rapid dearomatization, fluorination, and rearomatization processes, which represents a conceptually novel strategy of combining partial hydrogenation and electrophilic fluorination.

2014
Antonio Arcadi Emanuela Pietropaolo Antonello Alvino Véronique Michelet

The scope and limitations of gold-catalyzed tandem cycloisomerization/fluorination reactions of unprotected 2-alkynylanilines to have access to 3,3-difluoro-2-aryl-3H-indoles and 3-fluoro-2-arylindoles are described. An unprecedented aminoauration/oxidation/fluorination cascade reaction of 2-alkynylanilines bearing a linear alkyl group on the terminal triple bond is reported.

Journal: :Chemical communications 2005
Luca Bernardi Karl Anker Jørgensen

The direct chiral Lewis acidic enantioselective chlorination and fluorination of beta-keto phosphonates is presented; the chlorination proceeds in high yields and with up to 94% ee using NCS as the chloro source, while the fluorination with (PhSO2)2NF (NFSI) gives the optically active alpha-fluoro-beta-keto phosphonates in moderate to good yields and with up to 91% ee.

Journal: :Chemical science 2017
Desta Doro Bume Cody Ross Pitts Fereshte Ghorbani Stefan Andrew Harry Joseph N Capilato Maxime A Siegler Thomas Lectka

The ubiquitous ketone carbonyl group generally deactivates substrates toward radical-based fluorinations, especially sites closest to it. Herein, ketones are used instead to direct aliphatic fluorination using Selectfluor, catalytic benzil, and visible light. Selective β- and γ-fluorination are demonstrated on rigid mono-, di-, tri-, and tetracyclic (steroidal) substrates employing both cyclic ...

Journal: :Nano letters 2014
Qunyang Li Xin-Z Liu Sang-Pil Kim Vivek B Shenoy Paul E Sheehan Jeremy T Robinson Robert W Carpick

The addition of a single sheet of carbon atoms in the form of graphene can drastically alter friction between a nanoscale probe tip and a surface. Here, for the first time we show that friction can be altered over a wide range by fluorination. Specifically, the friction force between silicon atomic force microscopy tips and monolayer fluorinated graphene can range from 5-9 times higher than for...

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