Copper-Chitosan Beads as Efficient and Recyclable Heterogeneous Catalysts for C−H Oxidation and C−X Amination

Abstract

Uniform millimeter-sized copper-incorporated chitosan beads were easily prepared via a simple synthetic method as efficient bifunctional heterogeneous catalysts for C−H oxidation of alkylarenes to ketones and C−X amination of aryl halides with ammonia. These potent catalysts were compatible to various substrates, resulting in 2–97 and 39–99 % yields for the oxidation and amination reactions, respectively. Moreover, we highlight the dual roles of chitosan that it not only served as a versatile support to enhance the catalytic performance of copper active species, but it also acted as a base to promote the catalytic reactions. The catalysts are robust and could be employed under conventional heating or microwave irradiation for several times without deactivation or deformation. The bead shape of the catalysts provides easy separation and recyclability. Thus, chitosan and this preparation method may be exploited in the development of other transition metal catalyst beads for valuable organic reactions.