@article{FudickarVomdranLinker2006,
  author    = {Fudickar, Werner and Vomdran, Katja and Linker, Torsten},
  title     = {Auxiliary controlled singlet-oxygen ene reactions of cyclohexenes},
  series = {Tetrahedron},
  volume    = {62},
  journal   = {Tetrahedron},
  number    = {46},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2006.07.104},
  pages     = {10639 -- 10646},
  year      = {2006},
  abstract  = {The photooxygenation of homochiral cyclohexene ketals, which are easily available from 2-cyclohexenone and L-tartrates, affords hydroperoxides and after reduction the corresponding allylic alcohols in good yields and high regioselectivities. This can be rationalized by electronic repulsions in a perepoxide intermediate and provides evidence for unfavorable 1,3 diaxial interactions with a dioxolane oxygen atom. Only low stereoselectivities were observed, due to the flexibility of the cyclohexene ring. However, the diastereomers could be separated and after cleavage of the auxiliary, 4-hydroxy-2-cyclohexen-1-one was isolated in enantiomerically pure form, which can serve as a building block for natural product synthesis.},
  language  = {en}
}
@article{BauchFudickarLinker2021,
  author    = {Bauch, Marcel and Fudickar, Werner and Linker, Torsten},
  title     = {Stereoselective [4+2] Cycloaddition of Singlet Oxygen to Naphthalenes Controlled by Carbohydrates},
  series = {Molecules : a journal of synthetic chemistry and natural product chemistry},
  volume    = {16},
  journal   = {Molecules : a journal of synthetic chemistry and natural product chemistry},
  number    = {4},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules26040804},
  pages     = {17},
  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}
}