Spin Labelled C-Glycoside Analogs: Derivatives of 1,4-Anhydro-4-deoxy-2,3-O-cyclopentylidene-l,4-N-hydroxyimino-DL-erythrofuranose

A series of 2,3-O-cyclopentylidene C-glycoside analogs in which the furanose ring has been replaced with a N-hydroxypyrrolidine have been prepared. A structural study of these tricyclic compounds and the aminoxyl radicals thereof has been carried out using variable temperature 1 H NMR, X-ray diffraction, molecular dynamics and EPR spectroscopy. Both types of compounds, N-hydroxypyrrolidines and pyrrolidine N-oxyls, fundamentally prefer - in solutions- N-endo conformations over the alternate, N-exo forms found by X-ray diffraction studies and computed to be more stable by molecular dynamics.