Development of catalytic c-n bond forming reactions via C-H bond activation

Abstract

Part 1. Cobalt- and Manganese-Catalyzed Direct Amination of Azoles under Mild Reaction Conditions and the Mechanistic Details A new cobalt- or manganese-catalyzed amination of azoles has been developed using peroxide and an acid additive to couple various types of azoles with ammonia, and primary or secondary amines. The reaction is highly attractive from the synthetic point of view in that the catalyst loadings are low, optimal reaction conditions are mild, and substrate scope is broad. In addition, a mechanistic proposal is made on the basis of the kinetic isotope effects and isolation of amidine compounds. The present reaction, therefore, is anticipated to be a powerful tool for the synthesis of 2-aminoazoles which are an important pharmacophore of high biological activity.

Part 2. Rhodium-Catalyzed Intermolecular Amidation of Arenes with Sulfonyl Azides via Chelation-Assisted C-H Bond Activation Aryl amines are a key synthetic unit widely utilized in organic synthesis, coordination chemistry, materials science and pharmaceutical industry. Current routes to those compounds require either pre-functionalized starting materials or external oxidants, thus inevitably generating stoichiometric amounts of side wastes. We report herein a direct amidation reaction of arene carbon-hydrogen (C-H) bonds using sulfonyl azides as a source of the nitrogen group to release molecular nitrogen as the single by-product. The reaction is catalyzed by a cationic rhodium complex under external oxidant-free conditions and at the atmospheric environment. Preliminary mechanistic studies suggest that the amidation proceeds via the chelation-assisted C-H bond activation followed by a rhodium nitrenoid transfer pathway. A broad range of chelate group-containing arenes are selectively amidated with excellent functional group tolerance, thereby opening a new avenue to environmentally benign carbon-nitrogen (C-N) bond formation procedure which can be immediately applied to various synthe...