Aryne-Mediated [2,3]-Sigmatropic Rearrangement of Tertiary Allylic Amines

A new
strategy has been established for the [2,3]-sigmatropic rearrangement
of quaternary allylic ammonium ylides via in situ activation of tertiary
allylic amines with arynes under mild conditions. Using 2-(trimethylsilyl)­aryl
triflates as aryne precursors, a range of tertiary allylic amines
bearing electron-withdrawing groups underwent [2,3]-sigmatropic rearrangement
to furnish structurally diverse homoallylic amines in moderate to
good yields. The reaction enabled construction of quaternary stereocenters
with excellent enantiopurity and functionalized cyclopropanes with
extremely high diastereoselectivity.