Advances in C–CN Bond Formation via C–H Bond Activation

The cyano group is well known as a versatile intermediate for transformations into a multitude of useful functional groups such as carboxyl, carbamoyl, aminomethyl, carbonyl, and heterocycles. Moreover, benzonitriles and α-aminonitriles are practical synthetic and natural scaffolds. This paper reviews catalytic methodologies for direct cyanation reactions of C–H bonds. These are classified by the cyano-group sources and are sorted into three categories: (i) organic cyano-group sources, (ii) metallic cyano-group sources, and (iii) combined cyano-group sources. This review includes all the reported methods in the literature until the beginning of 2016.