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001-es BibID:BIBFORM004160
Első szerző:Linker, Torsten
Cím:Remarkable Oxidation Stability of Glycals : Excellent Substrates for Cerium(IV)-Mediated Radical Reactions / Torsten Linker, Dirk Schanzenbach, Elangovan Elamparuthi, Thomas Sommermann, Werner Fudickar, Viktor Gyóllai, László Somsák, Wolfgang Demuth, Michael Schmittel
Dátum:2008
Megjegyzések:The remarkable stability of glycals under oxidative conditions becomes apparent by their redox data in solution, computed HOMO energies, and behavior on the addition of electrophilic radicals generated in the presence of cerium(IV) ammonium nitrate. Oxidation potentials up to 2.03 V vs ferrocene were obtained, which are exceptionally high for cyclic enol ethers but correlate nicely with the reaction times of the radical reactions. Protecting groups have a strong influence on the oxidation stability and HOMO energies of glycals as Eox is shifted from O-silyl over O-benzyl to O-acetyl by more than 500 mV. Interestingly, this effect must be transmitted through ?-bonds, even up to the para-position of a benzoate group, as verified by a wide variation of remote substituents in the carbohydrate. Favorable interactions of the ?*-orbital of the adjacent C?O bond with the HOMO of the double bond are proposed as a mechanistic rationale, which might be important for the redox behavior of other allylic systems. Finally, donors and acceptors in the 1-position exert the strongest influence on the oxidation stability, shifting the potentials by almost 1 V and resulting in different follow-up reactions of the cerium(IV)-mediated additions of malonates. It is the remarkable oxidation stability of glycals that makes them valuable building blocks in carbohydrate chemistry.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of the American Chemical Society. - 130 : 47 (2008), p. 16003-16010. -
További szerzők:Schanzenbach, Dirk Elamparuthi, Elangovan Sommermann, Thomas Fudickar, Werner Gyóllai Viktor Demuth, Wolfgang Schmittel, Michael Somsák László (1954-) (vegyész)
Internet cím:DOI
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