ABSTRACT
A protocol of iridium catalyzed asymmetric hydrogenation of 4-alkyl substituted 3-ethoxycarbonyl quinolin-2-ones and coumarins has been reported, providing a wide range of chiral dihydroquinolin-2-ones and dihydrocoumarins in high yields with excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 28â¯000). This efficient protocol was successfully applied for the synthesis of MPR3160 and the key chiral intermediate of R-106578.
ABSTRACT
A highly efficient asymmetric hydrogenation of γ- and δ-ketoacids was developed by using a chiral spiro iridium catalyst (S)-1a, affording the optically active γ- and δ-hydroxy acids/lactones in high yields with excellent enantioselectivities (up to >99% ee) and turnover numbers (TON up to 100000). This protocol provides an efficient and practical method for enantioselective synthesis of Ezetimibe.
ABSTRACT
A new efficient and highly enantioselective direct asymmetric hydrogenation of α-keto acids employing the Ir/SpiroPAP catalyst under mild reaction conditions has been developed. This method might be feasible for the preparation of a series of chiral α-hydroxy acids on a large scale.
Subject(s)
Iridium/chemistry , Keto Acids/chemistry , Spiro Compounds/chemistry , Catalysis , Glyoxylates/chemistry , Hydrogenation , Mandelic Acids/chemistry , StereoisomerismABSTRACT
The first highly enantioselective iridium-catalyzed hydrogenation of cyclic enamines has been developed. This new reaction provided an efficient method for the synthesis of optically active cyclic tertiary amines including natural product crispine A.