Synthesis of Enantiomerically Enriched Mono and Bis 2,2'-Bipyridine Alkyl Sulfoxides and Their First Application as Chiral Auxiliaries1

The direct asymmetric oxidation of 6,6'-bis(alkylsulfanyl)-2,2'-bipyridines 2a-e to non-racemic mono sulfoxides 3a-e and bis-sulfoxides 4a,c-e using either Davis oxaziridine or a modified Sharples reagent is reported. The use of isolated mono- and bis-sulfoxides as chiral auxiliaries was tested in either the asymmetric addition of the diethylzinc or allyl(trichloro)silane to benzaldehyde.