An Improved Synthesis of Imidazo[4,5-b]pyridines and Imidazo[4,5-b]pyrazines by Palladium Catalyzed Amidation using Xantphos in a 1,4-Dioxane:tert-Amyl Alcohol Solvent System

The method represents an improved protocol of a previously published procedure which is also suitable for the coupling of substrates with electron-poor benzylic functionalities as well as an extended scope of amide coupling partners.