Sequential Isoprene Unit Elongation Reaction Based on Rearrangement Reaction

点击翻译按钮获取中文摘要

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.