title: Asymmetric conjugate reductions with samarium diiodide: asymmetric synthesis of (2S,3R)- and (2S,3S)-[2-2H,3-2H]-leucine-(S)-phenylalanine dipeptides and (2S,3R)-[2-(2)H,3-2H]-phenylalanine methyl ester.
abstract: The highly diastereoselective samarium diiodide and D(2)O-promoted conjugate reduction of homochiral (E)- and (Z)-benzylidene and isobutylidene diketopiperazines (E)-5,7 and (Z)-6,8 has been demonstrated. This methodology allows the asymmetric synthesis of methyl (2S,3R)-dideuteriophenylalanine 27 in > or = 95% de and >98% ee, and (2S,3R)- or (2S,3S)-dideuterioleucine-(S)-phenylalanine dipeptides 37 and 38 in moderate de, 66% and 74% respectively. A mechanism is proposed to account for this process.
authors.affiliation: Department of Organic Chemistry, University of Oxford, Chemistry Research Laboratory, UK. steve.davies@chem.ox.ac.uk
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Davies
authors.forename: Humberto
authors.initials: H
authors.lastname: Rodriguez-Solla
authors.forename: Juan A
authors.initials: JA
authors.lastname: Tamayo
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Cowley
authors.forename: Carmen
authors.initials: C
authors.lastname: Concellon
authors.forename: A Christopher
authors.initials: AC
authors.lastname: Garner
authors.forename: Alastair L
authors.initials: AL
authors.lastname: Parkes
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Smith
mesh_terms: D018360:Crystallography, X-Ray; D004151:Dipeptides / Q000138:chemical synthesis* / Q000737:chemistry; D007454:Iodides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D012493:Samarium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D004151:Dipeptides; D007454:Iodides; C119108:leucyl-phenylalanine; C034515:phenylalanine methyl ester; D012493:Samarium; D010649:Phenylalanine; C409809:samarium diiodide