title: Aza Cope rearrangement of propargyl enammonium cations catalyzed by a self-assembled "nanozyme".
abstract: The tetrahedral assembly [Ga4L6](12-) [L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga4L6](12-) assembly, rate accelerations by factors of up to 184 compared with the background reaction rate were observed. After rearrangement, the product iminium ion is released into solution and hydrolyzed, allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a decrease in the entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics: the rate data obeyed the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a nonreactive guest was demonstrated.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
authors.forename: Courtney J
authors.initials: CJ
authors.lastname: Hastings
authors.forename: Dorothea
authors.initials: D
authors.lastname: Fiedler
authors.forename: Robert G
authors.initials: RG
authors.lastname: Bergman
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Raymond
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry*; D001372:Aza Compounds / Q000737:chemistry*; D002384:Catalysis; D002412:Cations / Q000737:chemistry; D019277:Entropy; D005708:Gallium / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D046911:Macromolecular Substances / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000480:Alkynes; D001372:Aza Compounds; D002412:Cations; D008024:Ligands; D046911:Macromolecular Substances; D009942:Organometallic Compounds; D000644:Quaternary Ammonium Compounds; D015057:1-Naphthylamine; D005708:Gallium