Asymmetric Transfer Hydrogenation of <i>gem</i>‐Difluorocyclopropenyl Esters: Access to Enantioenriched <i>gem</i>‐Difluorocyclopropanes
Khalil Yamani, Hugo Pierre, Alexis Archambeau, Christophe Meyer, Janine Cossy
Abstract
Abstract Catalytic enantioselective access to disubstituted functionalized gem ‐difluorocyclopropanes, which are emerging fluorinated motifs of interest in medicinal chemistry, was achieved through asymmetric transfer hydrogenation of gem ‐difluorocyclopropenyl esters, catalyzed by a Noyori–Ikariya ( p ‐cymene)‐ruthenium(II) complex, with ( N ‐tosyl‐1,2‐diphenylethylenediamine) as the chiral ligand and isopropanol as the hydrogen donor. The resulting cis‐gem ‐difluorocyclopropyl esters were obtained with moderate to high enantioselectivity ( ee =66–99 %), and post‐functionalization reactions enable access to valuable building blocks incorporating a cis ‐ or trans ‐ gem ‐difluorocyclopropyl motif.