| Sakurai and Mukaiyama aldol additions were carried out with a beta-azido aldehyde under chelation and non-chelation conditions. The reactions were generally found to be diastereofacially selective in favor of the anti stereoisomer and showed simple diastereoselectivity in favor syn substitution. The relative stereochemistry of the addition products were deduced from NOE experiments on cyclic amines that were produced from intramolecular Schmidt, Staudinger/aza-Wittig, and catalytic hydrogenation reactions. The findings indicate that substituted N-heterocycles can be made diastereoselectively in a couple of steps from simple azido aldehydes by carefully selecting the reaction conditions. |
