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Keywords:

  • aluminum;
  • asymmetric catalysis;
  • enantioselectivity;
  • homogeneous catalysis;
  • N,O ligands

Abstract

Chiral AlIII salen complexes were synthesized and used as catalysts for the asymmetric hydrocyanation of nitroolefins using 4-phenylpyridine N-oxide as an additive and trimethylsilyl cyanide (TMSCN) as a source of cyanide. An excellent yield of β-nitronitrile (87 %) and enantioselectivity (90 %) were achieved if (2-nitrovinyl)cyclohexane was used as a substrate at −15 °C in 16 h. To understand the interaction of the AlIII salen complex and additive, NMR and IR spectroscopic studies revealed that 4-phenylpyridine N-oxide acts both as an axial ligand and helps to activate the cyanide source TMSCN, which thereby increases the reactivity. A catalytic cycle was proposed based on the spectroscopic studies.