Abstract
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.
Dedicated to Professor Marian Mikołajczyk, CBMiM PAN in Łódź, Poland, on the occasion of his 70th birthday.
Notes
a Davis protocol.
b Kagan protocol.
c ee was determined by 1H NMR using the CSA method.Citation 19
d ee was determined by HPLC analysis using a chiral stationary phase column (Chirobiotic T).
e Bis sulfoxide 4b was not isolated.
a Values calculated for enantiomerically pure ligands.
a Values calculated for enantiomerically pure ligands.