A Tetradentate Ligand Enables Iron-Catalyzed Asymmetric Hydrogenation of Ketones in a CO- or Isocyanide-Free Fashion

Abstract

We herein reported the design and synthesis of a ferrocene-based tetradentate ligand that is featured with modular synthesis and rigid skeleton. Its iron(II) complex facilitates asymmetric direct hydrogenation of ketones without the participation of extra strong-field ligand such as CO and isocyanide. Hydride donor lithium aluminum hydride (LAH) converted non-reactive Fe(II) species to reactive Fe(II) hydride species. With this catalyst, various chiral alcohols including the intermediate for montelukast could be prepared with satisfactory yields and enantioinduction.

Keywords: asymmetric hydrogenation; iron catalysis; ketone; strong-field ligand; tetradentate ligand.