Efficient and Diastereoselective Syntheses of C‐6 Homologues of DMJ, DNJ Iminosugars

Herein we present a simple and efficient strategy for the syntheses of d-mannose- and d-ribose-derived six-membered cyclic nitrones through a stereoselective intramolecular aza-Michael addition. These nitrones serve as common intermediates in the construction of biologically active glycosidase inhibitors, such as 6-homo-4-epi-1-deoxynojirimycin and 6-homo-5-epi-1-deoxymannonojirimycin, and further utilized in cycloaddition reactions with various dipolarophiles, yielding isoxazolidines with excellent regio- and stereoselectivity. This versatile strategy allows for the collective stereoselective total syntheses of various alkaloids, demonstrating its broad applicability in synthetic chemistry.