Novel polyhydroxylated derivatives of quinolizidine and decahydropyrido[1,2-a]azepine were prepared starting from a common oxazolidinone. The bicyclic cores were prepared by a ruthenium-catalyzed ring-closing metathesis, followed by re-use of the catalyst in the subsequent syrt-dihydroxylation in a one-pot procedure. (C) 2014 Elsevier Ltd. All rights reserved.
Carboxybenzyl Group as an <i>O</i>-Nucleophile in the C–H Allylic Oxidation: Total Synthesis of (−)-Castanospermine
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 stereoselectivesynthesis of unnatural (−)-castanospermine. Cyclization of the key intermediate with PhSeBr afforded the desired bicyclic scaffold. In an alternative route, hydroboration/oxidation followed