ABSTRACT
A new strategy for the synthesis of the title compounds via a regio- and chemoselective one-pot inter- and intramolecular Buchwald-Hartwig amination of 2-chloro-3-iodopyridine with aminoazines and -diazines is reported.
Subject(s)
Aza Compounds/chemical synthesis , Imidazoles/chemical synthesis , Organometallic Compounds/chemistry , Palladium/chemistry , Pyridines/chemical synthesis , Amidines/chemistry , Amination , Catalysis , Imidazoles/chemistry , Molecular StructureABSTRACT
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.
