Catalytic asymmetric sulfoxidation by chiral manganese complexes: acetylacetonate anions as chirality switches.
Three manganese(II) complexes, namely [Mn(1)(ClO(4))(2)] (3), [Mn(1)(acac)(2)] (4), and [Mn(2)(1)(acac)(4)] (5), were isolated from solutions of Mn(ClO(4))(2) or Mn(acac)(2), and an easily accessible diimine ligand (1S,2S)-N,N'-bis-pyridin-2-ylmethylene-cyclohexane-1,2-diamine (1). Their structure was determined by X-ray crystallography, and these complexes proved to be catalysts for asymmetric sulfide oxidation by H(2)O(2). Enantiomeric excesses ranging from 5% to 62% were obtained with a variety of aryl alkyl sulfides. We also observed an interesting "chirality switch" effect by the achiral acac anion reversing the enantioselectivity of the complex [Mn(1)(ClO(4))(2)] from the S to the R sulfoxide enantiomer.
Schoumacker
Sébastien
S
Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, DRDC-CB, UMR 5047 Université Joseph Fourier/CEA/CNRS, CEA Grenoble, 17 Avenue des Martyrs, 38054 Grenoble Cedex, France.
Hamelin
Olivier
O
Pécaut
Jacques
J
Fontecave
Marc
M