Highly enantioselective enone epoxidation catalyzed by short solid phase-bound peptides: dominant role of peptide helicity.
The series of L-Leu 1-20-mers, peptides carrying 1-5 N-terminal Gly residues, and oligomers of (S)-beta(3)-Leu and (1R,2R)-2-aminocyclohexanecarboxylic acid were synthesized on TentaGel S NH(2). Five L-Leu residues were found sufficient to catalyze the Juliá-Colonna epoxidation of chalcone with 96-98% ee. Experiment and molecular modeling suggest that catalysis is effected by binding of the enone to the N-terminus, and the helicity of the peptide determines the epoxide configuration through face-selective delivery of a hydroperoxide anion. [reaction: see text]
Berkessel
A
A
Institut für Organische Chemie der Universität zu Köln, Greinstrasse 4, D-50939 Köln, Germany. berkessel@uni-koeln.de
Gasch
N
N
Glaubitz
K
K
Koch
C
C
D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013237:Stereoisomerism
D004852:Epoxy Compounds; D010455:Peptides