Iridium catalyzed enantioselective hydrogenation of α-alkoxy and β-alkoxy vinyl ethers

Abstract

Iridium catalyzed, enantioselective hydrogenations of functionalized, acid-sensitive vinyl ethers are reported. These reactions are mediated by the chiral N-carbene–oxazoline complex 1 that, unlike similar N,P-ligated catalysts (6 and 7), gives hydrogenation products (with enantioselectivities up to 96%) without significant acid-mediated degradation. In general, higher enantioselectivities were observed for the allylic alcohol derivatives (2) than the α-methoxycinnamate-based compounds (4).