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

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. A ferrocene-based tetradentate ligand featured with modular synthesis and rigid skeleton was reported. Its iron(II) complex facilitates asymmetric direct hydrogenation of ketones without the participation of extra strong-field ligand such as CO and isocyanide. Various chiral alcohols including the intermediate for montelukast could be prepared with satisfactory yields and enantioinduction.image

Automated summary

A ferrocene-based tetradentate ligand with modular synthesis and rigid skeleton was designed and synthesized, and its iron(II) complex was found to facilitate the asymmetric direct hydrogenation of ketones without the need for strong-field ligands such as CO and isocyanide. The use of a hydride donor LiAlH4 converted non-reactive Fe(II) species to reactive Fe(II) hydride species, enabling the preparation of various chiral alcohols with satisfactory yields and enantioinduction, including the intermediate for montelukast.