Takeaki Katayama

Asymmetric Hydrogenation of Polysubstituted Aromatic Ketones Catalyzed by the DIPSkewphos/PICA Derivative–Ruthenium(II) Complexes

The DIPSkewphos/PICA derivative‐Ru(II) complexes catalyzed asymmetric hydrogenation of significantly sterically hindered 2’,3’,4’,5’,6’‐pentamethylacetophenone, which was not reduced with NaBH4 at 25 °C, with a substrate‐to‐catalyst molar ratio (S/C) of 2000 under 50 atm of H2 in a base‐containing 2‐propanol to afford the alcohol in 99 % ee quantitatively. A series of polysubstituted aromatic ketones was smoothly reacted with an S/C of 300–10,000 under 10–50 atm of H2, yielding the alcoholic products in up to 99 % ee. The catalyst system achieved an industrial‐scale (50 kg) hydrogenation of 2’,6’‐dichloro‐3’‐fluoroacetophenone, affording the alcohol in 96 % isolated yield and in 98 % ee. The obtained alcoholic product is known as a key intermediate for the synthesis of the medicine crizotinib.