@misc{BauchFudickarLinker2021,
  author    = {Bauch, Marcel and Fudickar, Werner and Linker, Torsten},
  title     = {Stereoselective [4+2] Cycloaddition of Singlet Oxygen to Naphthalenes Controlled by Carbohydrates},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1116},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-49336},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-493361},
  pages     = {19},
  year      = {2021},
  abstract  = {Stereoselective reactions of singlet oxygen are of current interest. Since enantioselective photooxygenations have not been realized efficiently, auxiliary control is an attractive alternative. However, the obtained peroxides are often too labile for isolation or further transformations into enantiomerically pure products. Herein, we describe the oxidation of naphthalenes by singlet oxygen, where the face selectivity is controlled by carbohydrates for the first time. The synthesis of the precursors is easily achieved starting from naphthoquinone and a protected glucose derivative in only two steps. Photooxygenations proceed smoothly at low temperature, and we detected the corresponding endoperoxides as sole products by NMR. They are labile and can thermally react back to the parent naphthalenes and singlet oxygen. However, we could isolate and characterize two enantiomerically pure peroxides, which are sufficiently stable at room temperature. An interesting influence of substituents on the stereoselectivities of the photooxygenations has been found, ranging from 51:49 to up to 91:9 dr (diastereomeric ratio). We explain this by a hindered rotation of the carbohydrate substituents, substantiated by a combination of NOESY measurements and theoretical calculations. Finally, we could transfer the chiral information from a pure endoperoxide to an epoxide, which was isolated after cleavage of the sugar chiral auxiliary in enantiomerically pure form.},
  language  = {en}
}
@misc{Linker2020,
  author    = {Linker, Torsten},
  title     = {Addition of Heteroatom Radicals to endo-Glycals},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {873},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-45997},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459970},
  pages     = {15},
  year      = {2020},
  abstract  = {Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon-carbon bonds. The formation of carbon-heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting from early examples, developed more than 50 years ago, the importance of such reactions for carbohydrate chemistry and recent applications will be discussed. After a short introduction, the mini-review is divided in sub-chapters according to the heteroatoms halogen, nitrogen, phosphorus, and sulfur. The mechanisms of radical generation by chemical or photochemical processes and the subsequent reactions of the radicals at the 1-position will be discussed. This mini-review cannot cover all aspects of heteroatom-centered radicals in carbohydrate chemistry, but should provide an overview of the various strategies and future perspectives},
  language  = {en}
}
@misc{KruegerKellingLinkeretal.2019,
  author    = {Krueger, Tobias and Kelling, Alexandra and Linker, Torsten and Schilde, Uwe},
  title     = {Crystal structures of three cyclohexane‑based γ‑spirolactams},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {738},
  doi       = {10.25932/publishup-43491},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434911},
  pages     = {9},
  year      = {2019},
  abstract  = {The title compounds, 2-azaspiro[4.5]deca-1-one, C₉H₁₅NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N-H···O hydrogen bonds.},
  language  = {en}
}
@misc{SchildeKellingUmbreenetal.2016,
  author    = {Schilde, Uwe and Kelling, Alexandra and Umbreen, Sumaira and Linker, Torsten},
  title     = {Crystal structures of three bicyclic carbohydrate derivatives},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-100833},
  pages     = {6},
  year      = {2016},
  abstract  = {The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis­(acet­yloxy)-7-oxo-2-oxabi­cyclo[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acet­yloxy-7-hy­droxy­imino-2-oxobi­cyclo­[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and [(3aR,5R,6R,7R,7aS)-6,7-bis­(acet­yloxy)-2-oxo­octa­hydro­pyrano[3,2-b]pyrrol-5-yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings.},
  language  = {en}
}
@misc{KlaperWessigLinker2015,
  author    = {Klaper, M. and Wessig, Pablo and Linker, Torsten},
  title     = {Base catalysed decomposition of anthracene endoperoxide},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-89676},
  pages     = {1210 -- 1213},
  year      = {2015},
  abstract  = {Catalytic amounts of a weak base are sufficient to induce the decomposition of anthracene endoperoxides to anthraquinone. The mechanism has been elucidated by isolation of intermediates in combination with DFT calculations. The whole process is suitable for the convenient generation of hydrogen peroxide under very mild conditions.},
  language  = {en}
}
@misc{GrottPeterLinkeretal.2003,
  author    = {Grott, Saskia and Peter, Martin G. and Linker, Torsten and Sefkow, Michael and Kroll, J{\"u}rgen and Koetz, Joachim and Laschewsky, Andr{\´e} and Lokatis, Siegfried and Rheinberg, Falko and Manig, Yvette},
  title     = {Portal = Chemie: Werkstoffe, Wirkstoffe, Lebensvorg{\"a}nge},
  number    = {01-02/2003},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-43971},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439713},
  pages     = {46},
  year      = {2003},
  abstract  = {Aus dem Inhalt: - Chemie: Werkstoffe, Wirkstoffe, Lebensvorg{\"a}nge - Institut f{\"u}r Kirchenrecht gegr{\"u}ndet - Computerlinguisten erstellen digitales W{\"o}rterbuch - Vom Spaß am Graffiti-Sprayen},
  language  = {de}
}