A new access to polyhydroxylated pyrrolidines from epoxyaldehydes

Our approach relies on the stereocontrolled vinylation of a chiral alpha,be ta -epoxyimine derived from the corresponding aldehyde. Regioselective open ing of the oxirane with carbonate anion allowed the formation of an oxazoli dinone intermediate from which the glucosidase inhibitor 1.4-dideoxy-1,4-im ino-D-glucitol (14) was synthesised. Direct cyclisation into a 2-vinyl-3.4- epoxypyrrolidine afforded a valuable intermediate for the preparation of sy nthetic azasugar analogues.