Asymmetric synthesis of chiral primary amines by transfer hydrogenation of N-(tert-butanesulfinyl)ketimines.
The diastereoselective reduction of (R)-N-(tert-butanesulfinyl)ketimines by a ruthenium-catalyzed asymmetric transfer hydrogenation process in isopropyl alcohol, followed by desulfinylation of the nitrogen atom, is an excellent method to prepare highly enantiomerically enriched alpha-branched primary amines (up to >99% ee) in short reaction times (1-4 h). (1S,2R)-1-Amino-2-indanol has been shown to be a very efficient ligand to perform this transformation. Ketimines bearing either an aryl or a heteroaryl group and an alkyl group as substituents of the iminic carbon atom are very good substrates for this process. The reduction of a dialkyl ketimine could also be achieved, affording the expected amine with moderate optical purity (69% ee). Some amines which are precursors of very interesting biologically and pharmacologically active compounds have been prepared in excellent yields and enantiomeric excesses.
Guijarro
David
D
Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain. dguijarro@ua.es
Pablo
Oscar
O
Yus
Miguel
M
D000588:Amines / Q000138:chemical synthesis* / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009570:Nitriles / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
D000588:Amines; D007097:Imines; D009570:Nitriles; C542835:ketimine; D006859:Hydrogen