Enantioselective Synthesis of Cyclic Nitrones by Chemoselective Intramolecular Allylic Alkylation of Oximes

다국어 초록 (Multilingual Abstract)

The enantio‐ and chemoselective iridium‐catalyzed N‐allylation of oximes is described for the first time. Intramolecular kinetic resolution provides access to cyclic nitrones and enantioenriched aliphatic allylic alcohols. Salient features of this transformation are its ability to employ E/Z‐isomeric mixtures of oxime starting materials convergently and high functional group tolerance. The implementation of N‐allylation/1,3‐dipolar cycloaddition reaction sequences furnishes tricyclic isoxazolidines in highly enantio‐ and diastereoselective fashion. The synthetic utility of the approach is demonstrated by the efficient, formal synthesis of the marine natural product (+)‐halichlorine.
The iridium‐catalyzed intramolecular chemo‐ and enantioselective N‐allylation of oximes is reported. The method employs E/Z mixtures of oximes and furnishes cyclic nitrones with high enantioselectivity. Tandem N‐allylation/dipolar cycloaddition sequences provide access to enantioenriched tricyclic isoxazolidines and enable the formal synthesis of the marine natural product Halichlorine.