title: Kinetic evidence of an apparent negative activation enthalpy in an organocatalytic process.
abstract: A combined kinetic and computational study on our tryptophan-based bifunctional thiourea catalyzed asymmetric Mannich reactions reveals an apparent negative activation enthalpy. The formation of the pre-transition state complex has been unambiguously confirmed and these observations provide an experimental support for the formation of multiple hydrogen bonding network between the substrates and the catalyst. Such interactions allow the creation of a binding cavity, a key factor to install high enantioselectivity.
authors.affiliation: KAUST Catalysis Center and Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.
authors.forename: Xiao
authors.initials: X
authors.lastname: Han
authors.forename: Richmond
authors.initials: R
authors.lastname: Lee
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.forename: Yixin
authors.initials: Y
authors.lastname: Lu
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Huang
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D003198:Computer Simulation; D004735:Energy Transfer; D019277:Entropy; D006860:Hydrogen Bonding; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D013890:Thiourea / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D014364:Tryptophan; D013890:Thiourea