Synthesis and conformational analysis of a novel type of spin labelled bicyclonucleoside based on a tetrahydrofurano[2,3-c]pyrrolidine sugar skeleton

Bicyclonucleosides bearing a 5-deoxy-5-N-hydroxyamino-3,N5-(1,1-ethano)-beta-D-furanosyl sugar moiety (15-18) have been prepared by glycosidation of the corresponding bicyclosugars obtained via an intramolecular reverse Cope elimination. The configuration of the asymmetric carbon of the 1,1-ethano bridge is the most important factor directing the conformation of the N-hydroxypyrrolidine ring and its invertomers ratio as shown by variable temperature H NMR experiments.