New chiral phosphoramidite complexes of iron as catalytic precursors in the oxidation of activated methylene groups

Molecules. 2010 Apr 12;15(4):2631-50. doi: 10.3390/molecules15042631.

Abstract

New phosphoramidite complexes of iron were synthesized and structurally characterized. Reaction of the known chiral phosphoramidites (RO)2PNR'2 (R = binaphthyl, R' = CH3, 1a; R = binaphthyl, R' = benzyl, 1b) with [FeBr(Cp)(CO)2] afforded the title compounds [FeBr(Cp)(CO)(1a,b)] (4a,b) in 34 and 65 % isolated yields as mixtures of diastereomers, since both the metal and the ligand are stereogenic. Similarly, reaction of 1b with [Fe(Cp)I(CO)2] in the presence of catalytic [Fe(Cp)(CO)2]2 afforded [Fe(Cp)I(CO)(1b)] (5b) in 81% yield as a mixture of diastereomers. The molecular structures of 4a, 4b and 5 were determined, revealing a pseudo octahedral coordination geometry about the iron center. The new metal complexes are catalytically active in the oxidation of benzylic methylene groups to the corresponding ketones, utilizing t-BuOOH as oxidant (2 mol% catalyst, 36 h, room temperature, 31-80% yield).

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetone / analogs & derivatives*
  • Acetone / chemistry
  • Catalysis
  • Coordination Complexes / chemistry*
  • Iron / chemistry*
  • Organophosphorus Compounds / chemistry*
  • Oxidation-Reduction

Substances

  • Coordination Complexes
  • Organophosphorus Compounds
  • phosphoramidite
  • Acetone
  • Iron
  • 1-phenyl-2-propanone