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T. Gobel

Bio: T. Gobel is an academic researcher from University of Basel. The author has contributed to research in topics: Radical & Radical cyclization. The author has an hindex of 2, co-authored 2 publications receiving 59 citations.

Papers
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Reference EntryDOI
Bernd Giese1, B. Kopping1, T. Gobel1, J. Dickhaut1, G. Thoma1, Klaus J. Kulicke1, F. Trach1 
TL;DR: Radical cyclization reactions are among the most powerful and versatile methods for the construction of mono-and polycyclic systems as discussed by the authors, which offer high functional group tolerance and mild reaction conditions combined with high levels of regio- and stereochemistry.
Abstract: Radical cyclization reactions are among the most powerful and versatile methods for the construction of mono- and polycyclic systems. The advantages these reactions offer to the synthetic organic chemist include high functional group tolerance and mild reaction conditions combined with high levels of regio- and stereochemistry. Furthermore, the recent progress in radical chemistry has led to the development of a broad range of very useful practical methods to conduct radical cyclization reactions. In general, radical cyclization reactions comprise three basic steps: selective radical generation, radical cyclization, and conversion of the cyclized radical to the product. For the generation of the initial radical a broad variety of suitable precursors can be employed, such as halides, thio- and selenoethers, alcohols, aldehydes and hydrocarbons. The cyclization step usually involves the intramolecular addition of a radical to a multiple bond. Most often carbon–carbon multiple bonds are employed; however, there are also examples known for the addition to carbon–oxygen and carbon–nitrogen bonds. Depending on the method employed, the cyclized radical is converted to the desired product by trapping with a radical scavenger, by a fragmentation reaction, or by an electron transfer reaction. The section Mechanism, Regio- and Stereochemistry provides an introduction to the key features of radical cyclization with a special emphasis on the factors controlling the regio- and stereochemistry. The section Scope and Limitations covers the different methods used to conduct radical cyclization. The basic principles of radical chemistry and general practical considerations when conducting radical cyclizations are not discussed in detail. Several excellent review articles and books dealing with these topics are available. Keywords: radical cyclization reactions; mechanism; regiochemistry; steroechemistry; small rings; scope; limitations; medium-sized rings; formation; monocycles; macrocyclizations; bi-cycles; polycycles; metal hydride; tin hydride; mercury hydride; fragmentation methods; thiohydroxamine; methods; Barton method; atom transfer; hydrogen atom transfer; halogen atom transfer; radical/radical coupling; redox methods; sequential reactions; experimental conditions; experimental procedures; comparison of methods; tabular survey

58 citations

Journal ArticleDOI
Bernd Giese1, B. Kopping1, T. Gobel1, J. Dickhaut1, G. Thoma1, Klaus J. Kulicke1, F. Trach1 
TL;DR: Radical cyclization reactions are among the most powerful and versatile methods for the construction of mono-and polycyclic systems as discussed by the authors, which offer high functional group tolerance and mild reaction conditions combined with high levels of regio- and stereochemistry.
Abstract: Radical cyclization reactions are among the most powerful and versatile methods for the construction of mono- and polycyclic systems. The advantages these reactions offer to the synthetic organic chemist include high functional group tolerance and mild reaction conditions combined with high levels of regio- and stereochemistry. Furthermore, the recent progress in radical chemistry has led to the development of a broad range of very useful practical methods to conduct radical cyclization reactions. In general, radical cyclization reactions comprise three basic steps: selective radical generation, radical cyclization, and conversion of the cyclized radical to the product. For the generation of the initial radical a broad variety of suitable precursors can be employed, such as halides, thio- and selenoethers, alcohols, aldehydes and hydrocarbons. The cyclization step usually involves the intramolecular addition of a radical to a multiple bond. Most often carbon–carbon multiple bonds are employed; however, there are also examples known for the addition to carbon–oxygen and carbon–nitrogen bonds. Depending on the method employed, the cyclized radical is converted to the desired product by trapping with a radical scavenger, by a fragmentation reaction, or by an electron transfer reaction. The section Mechanism, Regio- and Stereochemistry provides an introduction to the key features of radical cyclization with a special emphasis on the factors controlling the regio- and stereochemistry. The section Scope and Limitations covers the different methods used to conduct radical cyclization. The basic principles of radical chemistry and general practical considerations when conducting radical cyclizations are not discussed in detail. Several excellent review articles and books dealing with these topics are available. Keywords: radical cyclization reactions; mechanism; regiochemistry; steroechemistry; small rings; scope; limitations; medium-sized rings; formation; monocycles; macrocyclizations; bi-cycles; polycycles; metal hydride; tin hydride; mercury hydride; fragmentation methods; thiohydroxamine; methods; Barton method; atom transfer; hydrogen atom transfer; halogen atom transfer; radical/radical coupling; redox methods; sequential reactions; experimental conditions; experimental procedures; comparison of methods; tabular survey

6 citations


Cited by
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Journal ArticleDOI
TL;DR: Byproducts produced when treating perfluorooctanoic acid (PFOA) and PFOS in water using a plasma treatment process intentionally operated to treat these compounds slowly to allow for byproduct accumulation were quantified.
Abstract: Byproducts produced when treating perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in water using a plasma treatment process intentionally operated to treat these compounds slowly to allow for byproduct accumulation were quantified. Several linear chain perfluoroalkyl carboxylic acids (PFCAs) (C4 to C7) were identified as byproducts of both PFOA and PFOS treatment. PFOA, perfluorohexanesulfonate (PFHxS), and perfluorobutanesulfonate (PFBS) were also found to be byproducts from PFOS degradation. Significant concentrations of fluoride ions, inorganic carbon, and smaller organic acids (trifluoroacetic acid, acetic acid, and formic acid) were also identified. In addition to PFCAs, PFHxS, and PFBS, trace amounts of 43 PFOA-related and 35 PFOS-related byproducts were also identified using a screening and search-based algorithm. Minor concentrations of gas-phase byproducts were also identified (<2.5% of the F originally associated with the parent molecules) some of which are reported for the first time in perfluoroalkyl substance degradation experiments including cyclic perfluoroalkanes (C4F8, C5F10, C6F12, C7F14, and C8F16). The short chain PFCAs detected suggest the occurrence of a stepwise reduction of the parent perfluoroalkyl substances (PFAS) molecule, followed by oxidation of intermediates, perfluoroalkyl radicals, and perfluoro alcohols/ketones. Using a fluorine mass balance, 77% of the fluorine associated with the parent PFOA and 58% of the fluorine associated with the parent PFOS were identified. The bulk of the remaining fluorine was determined to be sorbed to reactor walls and tubing using sorption experiments in which plasma was not generated.

208 citations

Journal ArticleDOI
TL;DR: In this article, a novel method using cobalt catalysts (I) and irradiation with blue LEDs allows the intramolecular Heck-type coupling yield the corresponding cyclic products under mild conditions.
Abstract: A novel method using cobalt catalysts (I) and irradiation with blue LEDs allows the intramolecular Heck-type coupling yield the corresponding cyclic products under mild conditions.

187 citations

Book ChapterDOI
TL;DR: A review of the C-C bond-forming reactions in the field of titanocene mediated or catalyzed epoxide opening over the last 5 years or so can be found in this article.
Abstract: This review presents a description of the C–C bond-forming reactions that have emerged in the field of titanocene mediated or catalyzed epoxide opening over the last 5 years or so. The powerful tandem sequences for polycylization will be especially emphasized.

120 citations

Journal ArticleDOI
TL;DR: Tandem carbon-carbon bond-forming reactions were studied by using indium as a single-electron-transfer radical initiator and the radical addition-cyclization reaction of hydrazone gave the functionalized cyclic products.

69 citations

Journal ArticleDOI
TL;DR: In this paper, the degradation of PFOA in water by dielectric barrier discharge (DBD) plasma in a coaxial cylindrical structure with the assistance of peroxymonosulfate (PMS) was explored.

60 citations