Ruthenium-Lewis acid catalyzed asymmetric Diels-Alder reactions between dienes and alpha,beta-unsaturated ketones

Chemistry. 2007;13(12):3354-68. doi: 10.1002/chem.200600851.

Abstract

The complex [Ru(Cp)(R,R-BIPHOP-F)(acetone)][SbF(6)], (R,R)-1 a, was used as catalyst for asymmetric Diels-Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3-dimethylbutadiene) and alpha,beta-unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, alpha-bromovinyl methyl ketone and alpha-chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50-90 % and with enantioselectivities up to 96 % ee. Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90 % ee. alpha-Chlorovinyl methyl ketone performed better than alpha-bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95 % ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)((S,S)-BIPHOP-F)(mvk)][SbF(6)], (S,S)-1 b, and [Ru(Cp)((R,R)-Me(4)BIPHOP-F)(acrolein)][SbF(6)], (R,R)-2 b, provided the basis for a rationalization of the asymmetric induction.

MeSH terms

  • Alkadienes / chemistry*
  • Catalysis
  • Combinatorial Chemistry Techniques*
  • Hydrocarbons, Cyclic / chemistry
  • Ketones / chemistry*
  • Molecular Structure
  • Ruthenium / chemistry*
  • Stereoisomerism
  • Vinyl Compounds / chemistry

Substances

  • Alkadienes
  • Hydrocarbons, Cyclic
  • Ketones
  • Vinyl Compounds
  • Ruthenium