Anilines Formation via Molybdenum-Catalyzed Intermolecular Reaction of Ynones with Allylic Amines

The multi-substituted anilines are widely found in organic synthesis, medicinal chemistry and material science. The quest for robust and efficient methods to construct a diverse array of these compounds using readily accessible starting materials under simple reaction conditions is of utmost importance. Here, we report an unprecedented and efficient approach for the synthesis of 2,4-di and 2,4,6-trisubstituted anilines. With a simple molybdenum(VI) catalyst, a wide range of 2,4-di and 2,4,6-trisubstituted anilines were efficiently prepared in generally good to excellent yields from readily accessible ynones and allylic amines. The synthetic potential of this methodology was further underscored by its applications in several synthetic transformations, gram-scale reactions, and derivatization of bioactive molecules. Preliminary mechanistic studies suggested that this aniline formation might involve a cascade of aza-Michael addition, [1,6]-proton shift, cyclization, dehydration, 6π-electrocyclization, and aromatization. This novel strategy provided a robust, simple, and modular approach for the syntheses of various valuable di- or trisubstituted anilines, some of which were otherwise challenging to access.