title: Kinetic and stereochemical evidence for the involvement of only one proline molecule in the transition states of proline-catalyzed intra- and intermolecular aldol reactions.
abstract: Contrary to the widely accepted mechanism of the Hajos-Parrish-Eder-Sauer-Wiechert reaction, we have obtained evidence for the involvement of only one proline molecule in the transition states of both inter- and intramolecular aldol reactions. Our conclusions are based on kinetic measurements and the absence of nonlinear and dilution effects on the asymmetric catalysis, and are supported by B3LYP/6-31G* calculations. Complementary to recent theoretical studies, our results provide the foundation of a unified enamine catalysis mechanism of proline-catalyzed inter- and intramolecular aldol reactions.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Linh
authors.initials: L
authors.lastname: Hoang
authors.forename: S
authors.initials: S
authors.lastname: Bahmanyar
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
authors.forename: Benjamin
authors.initials: B
authors.lastname: List
mesh_terms: D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D007659:Ketones / Q000737:chemistry*; D007700:Kinetics; D011392:Proline / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D000447:Aldehydes; D007659:Ketones; D011392:Proline