Catalytic Asymmetric Sulfoxidation by Chiral Manganese Complexes: Acetylacetonate Anions as Chirality Switches
dataset
posted on 2003-12-01, 00:00 authored by Sébastien Schoumacker, Olivier Hamelin, Jacques Pécaut, Marc FontecaveThree manganese(II) complexes, namely [Mn(<b>1</b>)(ClO<sub>4</sub>)<sub>2</sub>] (<b>3</b>), [Mn(<b>1</b>)(acac)<sub>2</sub>] (<b>4</b>), and [Mn<sub>2</sub>(<b>1</b>)(acac)<sub>4</sub>] (<b>5</b>), were isolated
from solutions of Mn(ClO<sub>4</sub>)<sub>2</sub> or Mn(acac)<sub>2</sub>, and an easily accessible diimine ligand (1<i>S</i>,2<i>S</i>)-<i>N</i>,<i>N</i>‘-bis-pyridin-2-ylmethylene-cyclohexane-1,2-diamine (<b>1</b>). Their structure was determined by X-ray crystallography, and these
complexes proved to be catalysts for asymmetric sulfide oxidation by H<sub>2</sub>O<sub>2</sub>. 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(<b>1</b>)(ClO<sub>4</sub>)<sub>2</sub>] from the <i>S</i> to the <i>R</i>
sulfoxide enantiomer.
