Institut für Organische Chemie
Keywords: Aza Claisen rearrangements, stereochemistry, transannular reactions, natural product synthesis.
The stereoselective generation of defined optically active tertiary and quaternary carbon centers is still an actual problem in the synthesis of natural or pharmaceutically important products. The Claisen rearrangement often serves as a key step in the total synthesis of complex structures. A new zwitterionic aza Claisen rearrangement was developed in our group to achieve the efficient diastereoselective formation of optically active amides and medium-sized ring lactams bearing several stereogenic centers with defined configurations. The reaction was used to generate key intermediates in natural product synthesis, the enantioselective syntheses of some terpenoids and alkaloids have been successfully completed. Actually, the scope and the limitations of several aza Claisen rearrangements are studied including stereochemical and mechanistic questions. Furthermore, the rearrangement products with defined stereogenic centers are used for further investigations such as iodocyclizations, transannular reactions, radical processes and the total synthesis of optically active alkaloids, prostanoids and amino acids.