Contribution to the synthesis of polyhydroxylated indolizidines starting from sugar isothiocyanates

A straightforward stereoselective route towards castanospermine analogues starting from the corresponding d-gluco- and l-ido-hexofuranose isothiocyanates (5S)-2 and (5R)-2 is described. The key transformations of this approach rely on ring-closing metathesis and reductive amination to form the final polyhydroxylated indolizidines 10–13 in good overall yields.