Cobalt(II)-Catalyzed Proficient Synthesis of Enaminones from Aryl Alkenes and Amines

Abstract

A simple, cost-effective and modular strategy has been developed to synthesize synthetically and pharmaceutically active enaminones via oxidative amination of aryl alkenes with amines and CHCl3 using tert-butylhydrogen peroxide (TBHP) as an oxidant. Herein, we describe the synthesis of enaminones from vinyl arenes and sterically hindered diisopropylethylamine (DIPEA) by employing earth-abundant cobalt salt as a catalyst within very short reaction time for the first time. Furthermore, nitrogen and oxygen containing heterocyclic compounds have been synthesized from these highly functionalized enaminones. Moreover, various controlled experiments such as radical trapping reaction along with Hammett analysis with various type of substituents on the styrene ring unravel the detailed mechanism of this reaction pathway.