Reflection on the epimerization of the α-stereocenter of sugar nitrones leads to the conclusion that the process may occur through [1,4]-sigmatropic rearrangement. Participation of an ionic mechanism was excluded by a deuterium labeling experiment, and DFT calculations showed a reasonable energy barrier for the proposed [1,4]-shift. Products of the intramolecular 1,3-dipolar cycloaddition of the studied nitrones were utilized in the diversity-oriented synthesis of polyhydroxy derivatives of piperidine, indolizidine and quinolizidine. Minimal activity against the screened glucosidases and human melanoma cell lines was observed for some of the obtained compounds.