Asymmetric oxidation of sulfides catalyzed by vanadium(IV) complexes of dibromo- and diiodo-functionalized chiral Schiff bases
2006 (Chinese)In: Cuihuà xuébào, ISSN 0253-9837, Vol. 27, no 8, 743-748 p.Article in journal (Refereed) Published
The catalyst system of VO(acac)(2) and Schiff base ligands derived from 3,5-dibromo- or 3,5-diiodosalicylaldehyde and inexpensive chiral amino alcohols was prepared. This catalyst displayed good yields and moderate to high enantioselectivity for the asymmetric oxidation of aryl methyl sulfides at room temperature when 1% catalyst (VO(acac)(2)/ligand molar ratio of 1: 2) and H2O2 Oxidant were used. The ligands derived from ( S)valinol exhibited considerably higher enantioselectivity than those ligands derived from ( S)-phenylalaninol and (R)-leucinol. The enantiomeric excess values were improved up to 88% for methyl phenyl sulfoxide and 92% for methyl p-bromophenyl sulfoxide by slow dropwise addition of H2O2 with the ligand prepared from 3 15-diiodosalicylaldehyde and (s)-valinol. The present study showed that the catalytic efficiency of VO(acac)(2) /Schiff base systems could not be improved by the addition of carboxylic acids or carboxylate salts.
Place, publisher, year, edition, pages
2006. Vol. 27, no 8, 743-748 p.
bromine, iodine, Schiff base, chiral sulfoxide, vanadium, thioether, asymmetric oxidation, aqueous hydrogen-peroxide, tert-butyl disulfide, enantioselective oxidation, sulfoxides, h2o2
IdentifiersURN: urn:nbn:se:kth:diva-15998ISI: 000240609300019OAI: oai:DiVA.org:kth-15998DiVA: diva2:334040
QC 201005252010-08-052010-08-05Bibliographically approved