title: Mechanistic investigation of the 2,5-diphenylpyrrolidine-catalyzed enantioselective alpha-chlorination of aldehydes.
abstract: The mechanism for the 2,5-diphenylpyrrolidine-catalyzed enantioselective alpha-chlorination of aldehydes with electrophilic halogenation reagents has been investigated by using experimental and computational methods. These studies have led us to propose a mechanism for the reaction that proceeds through an initial N-chlorination of the chiral catalyst-substrate complex, followed by a 1,3-sigmatropic shift of the chlorine atom to the enamine carbon atom. The suggested reaction course is different from previously proposed mechanisms for organocatalytic enamine reactions, in which the carbon-electrophile bond is formed directly. Furthermore, the rate-determining step in the overall reaction was determined and the presence of nonlinear effects was probed.
authors.affiliation: Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: Nis
authors.initials: N
authors.lastname: Halland
authors.forename: Mette
authors.initials: M
authors.lastname: Alstrup Lie
authors.forename: Anne
authors.initials: A
authors.lastname: Kjaersgaard
authors.forename: Mauro
authors.initials: M
authors.lastname: Marigo
authors.forename: Birgit
authors.initials: B
authors.lastname: Schiøtt
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D002713:Chlorine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011759:Pyrrolidines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C515254:2,5-diphenylpyrrolidine; D000447:Aldehydes; D011759:Pyrrolidines; D002713:Chlorine