Fluorination of Glucopyranosides with DAST
447
1H couplings ꢀ2JF,H) and other diacritical data ꢀe.g. chemical shifts of H-2 and C-2, respectively) it
has to be concluded that the structure appointments are wrong in 8 cases. According to our
interpretation of the data, the methyl ꢀ-L-manno derivative as well as all thioglycosides ꢀꢀ- and
ꢁ-anomers from the D=L-gluco series) were subject to ASꢀ2,NG-1), whereas all O-glycosides with
ꢀ- or ꢁ-D=L-gluco con®guration, including those containing a 4,6-O-benzylidene protection, gave
MSꢀ2,rO) only. This is in full agreement with parameters we have deduced herein from our re-
sults, except that in the ꢀmore reactive) 3-deoxy-3-C-methyl-3-nitro-glucopyranose case, a 4,6-O-
benzylidene protection does no more cause prevention of the ring contractive MSꢀ2,rO)-reaction.
Acknowledgements
We appreciate ®nancial support by the Fonds zur Forderungder wissenschaftlichen Forschung ,
Vienna ꢀP-11021 OECH) and thank Chemprosa, Lannach ꢀAustria) for the gift of educts for this
investigation. Student coworkers in the synthesis of educts as well as their treatment with DAST have
been: R. Peinsipp, J. Wolfgang, G. Koller, B. J. Paul, F. Burghart, C. Gruber, W. Haas, M. Grininger,
R. Harrer, W. Kroutil, S. Leitgeb, M. Waldhuber, D. Kober, T. Sovic, and J. Steinreiber. They are all
thanked for their valuable help in these laborious studies.
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