Atroposelective Synthesis of Diarylamines via Organocatalyzed Electrophilic Amination
Zidan Ye, Wansen Xie, Donglei Wang, Hua Liu, Xiaoyu Yang
Abstract
Axially chiral diarylamine atropisomers represent a distinct category characterized by two contiguous chiral C–N axes, which exhibit a significantly lower racemization barrier due to the concerted rotation of both C–N axes. In this work, we introduce an effective method for the atroposelective synthesis of axially chiral diarylamines through organocatalyzed asymmetric electrophilic amination with azodicarboxylates, which afforded a variety of acyclic secondary diarylamine atropisomers in good yields with high enantioselectivities. This method expands the scope of catalytic asymmetric synthesis beyond N-aryl quinoid-type atropisomers, enabling the catalytic atroposelective synthesis of chiral diarylamines without constraining one C–N axis through intramolecular hydrogen bonding. Both experimental and computational studies show a minimal contribution of intramolecular hydrogen bonding in stabilizing configurations of these atropisomers, which undergo racemization via the concerted rotation of both C–N axes.