Sequential Isoprene Unit Elongation Reaction Based on Rearrangement Reaction

以季铵盐为原料，生成季铵盐，消除、异构化，再经水解得到(E)-醛，得到了高产率的[3，3]S型重排反应方法。本方法可以进行串联重排/还原，得到相应的胺。因此，季铵盐与t、BuOK或Net_3在正丁基硼烷存在下反应，首先进行氮杂-克莱森重排，然后还原得到(E)-氨基烯烃，产率较高。值得注意的是，本反应是通过串联消除/[3，3]-重排/还原机理进行的，其中包括叶立德的初始形成，然后消除成铵盐，生成的盐的[3，3]重排得到亚胺盐，后者通过氢化物还原得到烯丙基胺。

Methodology of[3, 3] sigmatropic rearrangement via generation of the enammonium salt from quaternary ammonium salt, elimination and isomerization, followed by hydrolysis to give(E)-aldehyde in good yield, was found out. The present method can be carried out the tandem rearrangement/reduction to give the corresponding amine. Thus, treatment of quaternary ammonium salt with t^BuOK or NEt_3 in the presence of pic-Borane resulted in aza-Claisen rearrangement, followed by reduction to give(E)-amino alkene in good yield. It should be noted that the present reaction proceeds via tandem elimination/[3, 3]-rearrangement/reduction mechanism which involves an initial formation of ylide followed by the elimination to the enammonium salt and the[3, 3] rearrangement of the resultant salt affords the iminium salt which gives the allylic amine by hydride reduction.