A short and efficient synthesis of 1-deoxy-castanospermine and 1-deoxy-8a-epi-castanospermine

A new route for the synthesis of 1-deoxy-castanospermine 2 and 1-deoxy-8a-epi-castanospermine 3 has been developed via a sequential triple reductive amination process of a suitably protected d-gluco-oct-5-ulo-1,8-dialdose, which was easily prepared by three carbon homologation of readily available α-d-xylo-pentodialdose using an appropriate Grignard reagent followed by oxidation.