ABSTRACT
The highly efficient asymmetric hydrogenation of alpha-arylmethylene cycloalkanones catalyzed by Ir-complexes of chiral spiro aminophosphine ligands was developed, providing chiral exo-cyclic allylic alcohols at high yields with excellent enantioselectivities (up to 97% ee) and high turnover numbers (S/C up to 10,000). This new reaction provided an efficient method for the synthesis of the key intermediate of the active form of the anti-inflammatory loxoprofen.
Subject(s)
Alcohols/chemical synthesis , Iridium/chemistry , Ketones/chemistry , Organometallic Compounds/chemistry , Phosphines/chemistry , Spiro Compounds/chemistry , Alcohols/chemistry , Catalysis , Hydrogenation , Ligands , Molecular Structure , StereoisomerismABSTRACT
A highly efficient enantio- and diastereoselective synthesis of chiral cis-beta-N-alkyl/arylamino cyclic alcohols has been realized by asymmetric hydrogenation of racemic alpha-amino cyclic ketones via DKR catalyzed by [RuCl(2)((S)-Xyl-SDP)((R,R)-DPEN)]. The enantioselectivities of the reaction were up to 99.9% ee with 99:1 cis-selectivities. A practical catalytic asymmetric synthesis of all four isomers of conhydrine was also developed.
Subject(s)
Alkaloids/chemical synthesis , Amino Alcohols/chemical synthesis , Piperidines/chemical synthesis , Ruthenium/chemistry , Alkaloids/chemistry , Amino Alcohols/chemistry , Catalysis , Hemlock/chemistry , Hydrogenation , Molecular Structure , Piperidines/chemistry , StereoisomerismABSTRACT
A highly efficient asymmetric hydrogenation of racemic acyclic alpha-amino aliphatic ketones via dynamic kinetic resolution has been realized, providing chiral amino alcohols in excellent enantioselectivities and diastereoselectivities. A hydrogen-bonding transition state mode was proposed for explaining the high diastereoselectivity and enantioselectivity of the reaction.