Cu-catalyzed aerobic oxidative dehydrogenation of tertiary indolines to indoles using azo/hydrazide redox

Abstract

Azo compounds are versatile in multifarious areas. They are crucial reagents in Mitsunobu reactions and dehydrogenations. However, the azo compounds or their corresponding hydrazides have never been investigated in the catalytic dehydrogenation of tertiary amines. Herein, we report a co-catalytic system using CuCl, 4-(dimethylamino)pyridine (DMAP), and 2-(4-nitrophenyl)hydrazine-1-carboxylate for the aerobic oxidative dehydrogenation of tertiary indolines to their corresponding indoles.