Study of a New Rate Increasing “Base Effect” in the Palladium-Catalyzed Amination of Aryl Iodides

Abstract
Evidence for an interphase deprotonation of Pd(II)−amine complexes with weak carbonate base has been gained for the first time. When a rate-limiting deprotonation step is involved in the catalytic cycle, controlling the structure (shape and size of the particles) and/or molar excess of the carbonate base used can significantly increase the reaction rate of Buchwald−Hartwig aminations. By taking such a “base effect” into account a general protocol for the intermolecular amination of aryl iodides with all types of amines has been developed based on a standard Pd−BINAP catalyst, using cesium carbonate as the base.