نتایج جستجو برای: intermediate radical

تعداد نتایج: 219788  

Journal: :Chemical communications 2015
Pan Xu Kaidong Hu Zhangxi Gu Yixiang Cheng Chengjian Zhu

A novel visible light promoted carbodifluoroalkylation of allylic alcohols is disclosed. A series of difluoro 1,5-dicarbonyl compounds were obtained through a tandem radical addition and 1,2-aryl migration process. Mechanistic analysis indicated that the 1,2-aryl rearrangement proceeded via a radical intermediate.

2006
Marc Moreno Maza Oleg Golubitsky Marina V. Kondratieva Alexey Ovchinnikov

Consider the Rosenfeld-Groebner algorithm for computing a regular decomposition of a radical differential ideal. We propose a bound on the orders of derivatives occurring in all intermediate and final systems computed by this algorithm. We also reduce the problem of conversion of a regular decomposition of a radical differential ideal from one ranking to another to a purely algebraic problem.

Journal: :Chemical communications 2010
Joseph W Tucker John D Nguyen Jagan M R Narayanam Scott W Krabbe Corey R J Stephenson

Herein, we report an advancement in the application of visible light photoredox catalysts in a classic free radical mediated reaction, cyclization onto unactivated pi-systems. The reactive radical intermediate is generated by the single electron reduction of an activated C-Br bond by an electron-rich redox catalyst afforded by a visible light induced catalytic cycle.

Journal: :Journal of the American Chemical Society 2002
Eun Jeong Jeong Eun Joo Kang Lee Taek Sung Sung Kil Hong Eun Lee

A macrodiolide antibiotic pamamycin-607 was synthesized by joining two hydroxy acid components. Three cis-2, 5-disubstituted tetrahydrofuran rings in the molecule were stereoselectively prepared by radical cyclization reactions of beta-alkoxyvinyl ketone intermediates and a beta-alkoxymethacrylate substrate. The key step of the synthesis is characterized by the predominant threo product formati...

2015
Juliana C. Ferreira Marcelo F. Marcondes Marcelo Y. Icimoto Thyago H. S. Cardoso Aryane Tofanello Felipe S. Pessoto Erica G. A. Miranda Tatiana Prieto Otaciro R. Nascimento Vitor Oliveira Iseli L. Nantes David Jourd'heuil

We characterized the peroxidase mechanism of recombinant rat brain cytoglobin (Cygb) challenged by hydrogen peroxide, tert-butylhydroperoxide and by cumene hydroperoxide. The peroxidase mechanism of Cygb is similar to that of myoglobin. Cygb challenged by hydrogen peroxide is converted to a Fe4+ oxoferryl π cation, which is converted to Fe4+ oxoferryl and tyrosyl radical detected by direct cont...

Journal: :Dalton Transactions 2021

Integrated experimental and computational studies reveal a new mechanism for Fe-catalyzed imidazoline synthesis through combined nitrene transfer acetonitrile attack of styrenyl radical intermediate.

2015
Shobha Chaturvedi Vibha Joshi

At high concentration of AA, the free radical intermediate of Pregnenolone is rapidly reduced by ascorbate, the latter getting oxidized; the onward oxidation of pregnenolone proceeds when AA content is depleted to the the level that would fail to reduce the free radical form of pregnenolone and and pregnenolone then is rapidly oxidized

Journal: :Chemical communications 2014
Pooja Yadav Andrew J Marshall Jóhannes Reynisson William A Denny Michael P Hay Robert F Anderson

The ˙OH radical is released from 3-trifluoromethyl-quinoxaline 1,4-dioxides upon one-electron reduction by cytochrome P450 oxidoreductase. This process effectively competes with back oxidation of the intermediate radical anion by oxygen and underlies the increased aerobic cytotoxicity of such compounds compared to that seen for the related clinical bioreductive benzotriazine drug, tirapazamine.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1971
T A Halgren J L Firkins T A Fujimoto H H Suzukawa J D Roberts

Studies of product compositions and deuterium-label rearrangements at various concentrations of tri-n-butyltin hydride in the reductions of exo-and endo-5-bromonorbornene and 2-bromonortricyclcne to mixtures of norbornene and nortricyclene lead to three main conclusions: (i) at least two radical intermediates contribute to product formation; (ii) each intermediate yields predominantly (80% or m...

Journal: :Organic & biomolecular chemistry 2005
W Russell Bowman Martin O Cloonan Anthony J Fletcher Tobias Stein

Cascade radical cyclisation involving homolytic aromatic substitution has been used to synthesise new tetracycles. Treatment of vinyl iodide radical precursors with Me(3)Sn. radicals (from hexamethylditin) yielded intermediate vinyl radicals which undergo 5-exo cyclisation onto suitably placed nitrile groups to yield intermediate iminyl radicals. The iminyl radicals undergo aromatic homolytic s...

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