Biomimetic and organocatalytic approaches to oxidation catalysis*
Albrecht Berkessel
Department of Organic Chemistry, Cologne University, Greinstrasse 4, D-50939 Cologne, Germany
Abstract: The lecture summarized our recent work in the fields of (i) catalytic asymmetric epoxidation and cyclopropanation, (ii) C–C coupling reactions, and (iii) dynamic kinetic resolution (DKR). The first section describes the use of chiral Ru-porphyrins as catalysts for the asymmetric epoxidation and cyclopropanation of nonfunctionalized olefins, and of peptides and alkaloid-based phase-transfer catalysts for the asymmetric epoxidation of enones. The second section highlights the application of the DIANANE-salen ligands (DIANANE: endo,endo-2,5-diamino-norbornane) to the asymmetric Nozaki–Hiyama–Kishi coupling of aldehydes with allylic and vinylic electrophiles, and of N-tosyl proline amides for asymmetric aldol additions. In the final section, bifunctional urea-based organocatalysts for the DKR of azlactones to provide enantiomerically enriched amino acid esters are presented.
Keywords: Biomimetic oxidation catalysis; organocatalysis; amino acids; asymmetric epoxidation; cyclopropanation; C–C coupling; dynamic kinetic resolution; Ru-porphyrins; DIANANE; Nozaki–Hiyama–Kishi coupling.
*An issue of reviews and research papers based on lectures presented at the 15th International Conference on Organic Synthesis (ICOS-15), held in Nagoya, Japan, 1-6 August 2004, on the theme of organic synthesis. Other presentations are published in this issue, pp. 1087-1296.