Divergent synthesis of benzazepines and bridged polycycloalkanones via dearomative rearrangement
Qiu Shi, Zhehui Liao, Zhili Liu, Jiajia Wen, Chenguang Li, Jiamin He, Jiazhen Deng, Shan Cen, Tongxiang Cao, Jinming Zhou, Shifa Zhu
Abstract
The dearomative functionalization of aromatic compounds represents a fascinating but challenging transformation, as it typically needs to overcome a great kinetic barrier. Here, a catalyst-free dearomative rearrangement of o-nitrophenyl alkyne is successfully established by leveraging the remote oxygen transposition and a weak N-O bond acceleration. This reaction features high atom-, step- and redox-economy, which provides a divergent entry to a series of biologically important benzazepines and bridged polycycloalkanones. The reaction is proposed to proceed through a tandem oxygen transfer cyclization/(3 + 2) cycloaddition/(homo-)hetero-Claisen rearrangement reaction. The resulting polycyclic system is richly decorated with transformable functionalities, such as carbonyl, imine and diene, which enables diversity-oriented synthesis of alkaloid-like polycyclic framework.