Stereoselective synthesis and glycosidase inhibitory activity of 3,4-dihydroxy-pyrrolidin-2-one, 3,4-dihydroxy-piperidin-2-one and 1,2-dihydroxy-pyrrolizidin-3-one

3,4-Dihydroxy-pyrrolidin-2-one, 3,4-dihydroxy-piperidin-2-one and 1,2-dihydroxy-pyrrolizidin-3-one have been synthesized, using a simple strategy based on the asymmetric dihydroxylation of vinylogous aminoesters and subsequent mild intramolecular cyclization. All these compounds show a partial inhibition of α-glucosidase, but were inactive towards other glycosidases.