Rh(III)-Catalyzed C(8)-H Activation of Quinoline N-Oxides: Regioselective C-Br and C-N Bond Formation

Abstract

A highly efficient and regioselective Rh(III)-catalyzed protocol for C8-bromination and amidation of quinoline N-oxide was developed. The transformation was found to be successful up to gram scale with excellent functional group tolerance and wide substrate scope. The mechanistic study revealed five-membered rhodacycle with quinoline N-oxide as a key intermediate for regioselective C8-functionalization. In addition, NFSI (N-fluorobis(phenylsulfonyl)-imide) was explored as an amidating reagent for C8-amidation of quinoline N-oxide for the first time.