Application of the Mitsunobu reaction to ephedrines and some related amino alcohols. Aspects of intramolecular participation of the amino group
作者:Martin A. Poelert、Richard M. Kellogg、L. A. Hulshof
DOI:10.1002/recl.19941130704
日期:——
at the benzylic hydroxyl group of (1S,2S)-pseudoephedrine (2) to afford (1R,2S)-ephedrine is known to be a difficult process. The Mitsunobu reactions of 1 and 2 might offer a route to achieve such inversions. In fact Mitsunobu reactions on 1 and 2 are known to proceed via aziridines formed on intramolecular SN2 substitution by the amine functionality. The Mitsunobu reactions of N-methylated and N-benzylated
已知将(1S,2S)-伪麻黄碱(2)的苄基羟基上的构型反转以得到(1R,2S)-麻黄碱是一个困难的过程。1和2的Mitsunobu反应可能会提供实现此类反演的途径。实际上,已知在1和2上的Mitsunobu反应是通过分子内S N 2被胺官能团取代形成的氮丙啶进行的。已经发现N-甲基化和N-苄基化的麻黄碱的Mitsunobu反应通过相应的叠氮鎓离子进行。这些吖丙啶鎓离子可以被打开(小号N 2取代)被邻苯二甲酰亚胺和硫醇等亲核试剂所取代。通过使用叔丁氧羰基-(BOC)或苄氧羰基-(CBZ)保护的衍生物,可以避免分子内参与2。这些衍生物上的Mitsunobu反应导致苄基羟基中心的构型反转。相反,1的BOC和CBZ衍生物在Mitsunobu条件下脱保护。的光延反应苏式(1小号,2,小号也已经研究了)-2-氨基-1,3-丙二醇。通过与二甲基甲酰胺二甲基乙缩醛反应实现保护的尝试导致了通过X射线晶体学确