Structural optimization of thiourea-based bifunctional organocatalysts for the highly enantioselective dynamic kinetic resolution of azlactones.
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%.
Berkessel
Albrecht
A
Institut für Organische Chemie der Universität zu Köln, Greinstrasse 4, D-50939 Köln, Germany. berkessel@uni-koeln.de
Mukherjee
Santanu
S
Müller
Thomas N
TN
Cleemann
Felix
F
Roland
Katrin
K
Brandenburg
Marc
M
Neudörfl
Jörg-M
JM
Lex
Johann
J
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*
D000588:Amines; D003959:Diamines; D007783:Lactones; D013890:Thiourea