Iridium-Catalyzed Asymmetric Hydrogenation of Racemic β‑Keto Lactams via Dynamic Kinetic Resolution

A highly efficient Ir-catalyzed asymmetric
hydrogenation of racemic
β-keto lactams via dynamic kinetic resolution (DKR) for the
synthesis of optically active β-hydroxyl lactams has been described.
With the Ir-SpiroSAP catalyst, a series of racemic β-keto lactams
including β-keto γ-, δ-, and ε-lactams were
hydrogenated to chiral β-hydroxy lactams in high yields (87–99%)
with excellent enantio- and diastereoselectivity (83–99.9%
ee, syn/anti: 97:3–>99:1)
at low catalyst loading under mild reaction conditions. This efficient
method has been successfully applied in the synthesis of the chiral
intermediate of fluoroquinolone antibiotic premafloxacine.