Enantioselective syntheses of organosulfur compounds via [2,3] sigmatropic rearrangements of ylides derived from di(allyl), di(propargyl), and di(benzyl) sulfide complexes; Control of carbon configuration by an easily resolved and recycled rhenium auxiliary
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The [2,3] sigmatropic rearrangement of sulfur ylides with S-allyl or related substituents finds widespread use in organic synthesis, but enantioselective versions of this carbon-carbon bond forming reaction are relatively unexplored. We report that the chiral rhenium Lewis acid [η5-C5H5)Re(NO)(PPh3)] + is a highly effect-ive auxiliary for desymmetrizations of di(allyl), di(propargyl), and di(benzyl) sulfides. Additions of t-BuOK to the air-stable cationic sulfide adducts give neutral thiolate complexes of high diastereomeric purities. The thiolate ligands can be S-alkylated and detached as sulfides of high enantiomeric purities. The rhenium auxiliary is easily recovered and recycled without loss of configuration. Crystal structures establish product configurations, and mechanisms of diastereoselection are analyzed in detail.
author list (cited authors)
Meyer, O., Cagle, P. C., Weickhardt, K., Vichard, D., & Gladysz, J. A.