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

The [2,3] sigmatropic rearrangement of sulfur ylides with S-allyl or r elated substituents finds widespread use in organic synthesis, but ena ntioselective versions of this carbon-carbon bond forming reaction are relatively unexplored. We report that the chiral rhenium Lewis acid [ (eta(5)-C5H5)Re(NO)(PPh(3))](+) is a highly effective auxiliary for de symmetrizations of di(allyl), di(propargyl), and di(benzyl) sulfides. Additions of t-BuOK to the air-stable cationic sulfide adducts give ne utral thiolate complexes of high diastereomeric purities. The thiolate ligands can be S-alkylated and detached as sulfides of high enantiome ric purities. The rhenium auxiliary is easily recovered and recycled w ithout loss of configuration. Crystal structures establish product con figurations, and mechanisms of diastereoselection are analyzed in deta il.