C–H Activation Guided by Aromatic N–H Ketimines: Synthesis of Functionalized Isoquinolines Using Benzyl Azides and Alkynes

Aromatic
N–H ketimines were in situ generated from various benzylic
azides by ruthenium catalysis for the subsequent Rh-catalyzed annulation
reaction with alkynes to give the corresponding isoquinolines. In
contrast to conventional synthetic methods for aromatic N–H
ketimines, our protocol works under mild and neutral conditions, which
enabled the synthesis of isoquinolines having various functionalities
such as carbonyl, ester, alkenyl, and ether groups. In addition, the
imidates generated from α-azido ethers were successfully used
for the synthesis of 1-alkoxyisoquinolines.