Organocatalytic syn-Aldol Reactions of Dioxanones with (S)-Isoserinal Hydrate: Synthesis of l -Deoxymannojirimycin and l -Deoxyidonojirimycin

We report a new protocol for synthesis of L-1-deoxymannojirimycin, L-1-deoxyidonojirimycin, and the N-isopropyl derivative of the latter compound from the readily available precursors (S)-isoserinal hydrate and 2-tert-butyl-2-methyl-1,3-dioxan-5-one. The key steps include diastereoselective proline-catalyzed syn aldol transformation and a reductive amination/cyclization.