title: Structural optimization of thiourea-based bifunctional organocatalysts for the highly enantioselective dynamic kinetic resolution of azlactones.
abstract: This article describes the synthesis of a library of structurally diverse bifunctional organocatalysts bearing both a quasi-Lewis acidic (thio)urea moiety and a Brønsted basic tertiary amine group. Sequential modification of the modular catalyst structure and subsequent screening of the compounds in the alcoholytic dynamic kinetic resolution (DKR) of azlactones revealed valuable structure-activity relationships. In particular, a "hit-structure" was identified which provides e.g.N-benzoyl-tert-leucine allyl ester in an excellent enantiomeric excess of 95%.
authors.affiliation: Institut für Organische Chemie der Universität zu Köln, Greinstrasse 4, D-50939 Köln, Germany. berkessel@uni-koeln.de
authors.forename: Albrecht
authors.initials: A
authors.lastname: Berkessel
authors.forename: Santanu
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Müller
authors.forename: Felix
authors.initials: F
authors.lastname: Cleemann
authors.forename: Katrin
authors.initials: K
authors.lastname: Roland
authors.forename: Marc
authors.initials: M
authors.lastname: Brandenburg
authors.forename: Jörg-M
authors.initials: JM
authors.lastname: Neudörfl
authors.forename: Johann
authors.initials: J
authors.lastname: Lex
mesh_terms: D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D018360:Crystallography, X-Ray; D003959:Diamines / Q000737:chemistry; D007700:Kinetics; D007783:Lactones / Q000737:chemistry*; D013237:Stereoisomerism; D013890:Thiourea / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D000588:Amines; D003959:Diamines; D007783:Lactones; D013890:Thiourea