The Synthesis of (2S,3R)-2-Hydroxymethylpiperidin-3-ol, a Fragment of the Alkaloid Swainsonine

Methyl α- and β-D-galactopyranoside have been converted into methyl 4,6-di-O-benzyl-2,3-dideoxy-α- and -β-D-threo-hexoside , and subsequent treatment with ethanedithiol gives the same alcohol. Tosylation and azide displacement gives, after hydrolysis, an azido aldehyde which is transformed under reducing conditions into the title piperidine . The synthetic piperidine is an ineffective inhibitor of α-D- mannosidase.