The synthesis of novel polyhydroxylated quinolizidines and azaspiro[4.5]decanes is reported. A key step of this transformation involved an addition of allylmagnesium bromide to an ω-bromonitrile derived from D-xylose followed by an intramolecular displacement of a bromide. The resulting cyclic imine was treated either with allylmagnesium bromide or with NaBH4, to provide 2,2-diallyl- or 2-allylpiperidine, respectively. The desired bicyclic framework was constructed via a ring-closing metathesis reaction. The Ru catalysts were reused in the following syn-dihydroxylation step.

The first palladium-mediated C-H allylic oxidation with a Cbz group acting as an O-nucleophile is reported. It was found that this transformation is promoted by rare-earth metal triflates: Yb(OTf)(3) or Sc(OTf)(3). A possible catalytic cycle is proposed. This reaction was applied in the synthesis of a d-xylose derived oxazolidinon, a versatile intermediate used further in the stereoselective synthesis of unnatural (-)-castanospermine. Cyclization of the key intermediate with PhSeBr afforded the desired bicyclic scaffold. In an alternative route, hydroboration/oxidation followed by DPPA-mediated cyclization was used.