Polyhydroxylated alkaloids or iminosugars,the nitrogen-in-the-ring analogues of furanose or pyranose,have attracted considerable attentions for their remarkable biological activities and potential as pharmaceuticals.Up to now,more than 200 iminosugars have been isolated from plants or bacteria.1 Although many elegant synthetic procedures have already been developed for the synthesis of iminosugars,there still lack of efficient methods for the rapid generation of iminosugars with structural diversities which is essential for in-depth structure-activity study.Recently,we and a number of others have shown that sugar-derived cyclic nitrones2 are powerful synthons for the diversity-oriented synthesis of iminosugars.