Enantiopure p,p′-disubstituted 1,2-diphenylethane-1,2-diols as chiral inducers in the Ti-mediated oxidation of sulfides: a case of reversal of asymmetric induction by fluorine substitution

✍ Scribed by Stefano Superchi; Maria Irene Donnoli; Carlo Rosini

• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 231 KB
• Volume: 39
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(98)01907-8

✦ Synopsis

In the asymmetric oxidation of methyl p-tolyl sulfide, (2a), and benzyl phenyl sulfide (2b) by TBHP, mediated by a titanium complex with enantiopure (R,R)-p,p'-disubstituted-l,2diphenylethane-l,2-diols, both the unsubstituted diol (R,R)-la and the p-OMe substituted diol (R,R)lb lead to sulfoxides of S configuration, with ee up to 99%. On the contrary the p-CF3 substituted ligand (R,R)-lc leads to significantly lower ee and in the case of 2a a reversal of asymmetric induction is observed.