A Configurational Switch Based on Iridium-Catalyzed Allylic Cyclization: Application in Asymmetric Total Syntheses of Prosopis, Dendrobate, and Spruce Alkaloids
作者:Christian Gnamm、Kerstin Brödner、Caroline M. Krauter、Günter Helmchen
DOI:10.1002/chem.200901316
日期:2009.10.12
A method for the stereoselectivesynthesis of 2,6‐disubstituted piperidines has been developed that is based on the use of an intramolecular iridium‐catalyzed allylic substitution as a configurational switch. The procedure allows the preparation of 2‐vinylpiperidines with enantiomeric excesses (ee) of greater than 99 %. As applications, total syntheses of piperidine alkaloids have been elaborated,
Stereoselective Synthesis of β-Proline Derivatives from Allylamines via Domino Hydroformylation/Wittig Olefination and Aza-Michael Addition
作者:Andreas Farwick、Günter Helmchen
DOI:10.1002/adsc.201000016
日期:——
Under appropriate reaction conditions, a domino hydroformylation/Wittigolefination can be accomplished with derivatives of allylamines and stabilized Wittig ylides. A further highly diastereoselective aza‐Michael reaction yields β‐proline derivatives. These are, for example, useful as building blocks for alkaloid syntheses.