ENANTIOPURE P,P'-DISUBSTITUTED 1,2-DIPHENYLETHANE-1,2-DIOLS AS CHIRALINDUCERS IN THE TI-MEDIATED OXIDATION OF SULFIDES - A CASE OF REVERSAL OF ASYMMETRIC INDUCTION BY FLUORINE SUBSTITUTION

In the asymmetric oxidation of methyl p-tolyl sulfide, (2a), and benzy l phenyl sulfide (2b) by TBHP, mediated by a titanium complex with ena ntiopure )-p,p'-disubstituted-1,2-diphenylethane-1,2-diols, both the u nsubstituted diol (R,R)-1a and the p-OMe substituted diol (R,R)Ib lead to sulfoxides of S configuration, with ee up to 99%. On the contrary the p-CF3 substituted ligand (R,R)-1c leads to significantly lower ee and in the case of 2a a reversal of asymmetric induction is observed. (C) 1998 Elsevier Science Ltd. All rights reserved.