title: Linking conformational flexibility and kinetics: catalytic 1,4-type Friedel-Crafts reactions of phenols utilizing 1,3-diamine-tethered guanidine/bisthiourea organocatalysts.
abstract: Herein, we present details of our conformationally flexible, 1,3-diamine-tethered guanidine/bisthiourea organocatalysts for chemo-, regio-, and enantioselective 1,4-type Friedel-Crafts reactions of phenols. These organocatalysts show a unique stereo-discrimination governed by the differential activation entropy (ΔΔS(≠)), rather than by the differential activation enthalpy (ΔΔH(≠)). Extensive kinetic analyses using Eyring plots for a series of guanidine/bisthiourea organocatalysts revealed the key structural motif in the catalysts associated with a large magnitude of differential activation entropy (ΔΔS(≠)). A plausible guanidine-thiourea cooperative mechanism for the enantioselective Friedel-Crafts reaction is proposed.
authors.affiliation: Department of Biotechnology and Life Science, Faculty of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan. sohtome@riken.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sohtome
authors.forename: Bongki
authors.initials: B
authors.lastname: Shin
authors.forename: Natsuko
authors.initials: N
authors.lastname: Horitsugi
authors.forename: Keiichi
authors.initials: K
authors.lastname: Noguchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nagasawa
mesh_terms: D002384:Catalysis; D003959:Diamines / Q000737:chemistry*; D019277:Entropy; D019791:Guanidine / Q000737:chemistry*; D007700:Kinetics; D010636:Phenols / Q000737:chemistry*; D013237:Stereoisomerism; D013890:Thiourea / Q000737:chemistry*
chemical_list: D003959:Diamines; D010636:Phenols; D013890:Thiourea; D019791:Guanidine