PPM Ir-f-phamidol-Catalyzed Asymmetric Hydrogenation of γ-Amino Ketones Followed by Stereoselective Cyclization for Construction of Chiral 2-Aryl-pyrrolidine Pharmacophores.

Transition metal catalysts with a million turnovers and excellent selectivity are rarely reported but are crucial for the industrial manufacture of optical pure pharmaceuticals, natural products, and fine chemicals. In this paper, we report an unprecedented aninoic Ir-f-phamidol catalyst for asymmetric hydrogenation of γ-amino ketones followed by stereoselective cyclization for construction of valuable chiral 2-aryl-pyrrolidine pharmacophores. The Ir-f-phamidol catalyst showed up to 1,000,000 TON and >99% ee, as well as excellent tolerance of substrates and protecting groups, providing various chiral amino alcohol intermediates. Upon optimization of the conditions, the stereoselective cyclization reaction was highly smooth and efficient (quantitative conversions, 92 to >99% ee). Finally, this solution was applied in the preparation of high-value chiral entities containing such chiral 2-aryl-pyrrolidine pharmacophores.