Sustainable Synthesis of Diverse Privileged Heterocycles by Palladium-Catalyzed Aerobic Oxidative Isocyanide Insertion

Heterocycles containing a guanidine moiety are of great importance in medicinal chemistry (Scheme 1).[1] As a result, several methods for the synthesis of these "privileged scaffolds" have been reported.[2, 3] Classical approaches, such as the addition of diamines to isothiocyanates followed by condensation and the coupling of diamines with cyanogen bromide,[2, 4] have some clear limitations, such as the availability and toxicity of reagents. Moreover, these procedures suffer from poor atom and/or step efficiency, thus making them unattractive from a sustainability point of view. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim