piperidine analogues of the pyrrolidine alkaloids radicamine A and radicamineB, were prepared from six-membered cyclic nitrones through a concise two-step procedure, i.e., Grignard reagent addition and deprotection. These novel polyhydroxylated piperidine iminosugars were assayed against 10 types of enzymes. Only compound 8 exhibited weak inhibition (IC50 1080 μmol/L) against β-galactosidase from rat