A cyano group is a strong electron withdrawing group and a number of cyanating reagents are widely used in organic synthesis. The cyano group is converted to other functional groups such as carboxylic acids or amides by hydrolysis, and is also converted to amines or aldehydes by reduction with some reducing reagents. Furthermore, alkyl nitriles which are typical cyano group containing compounds are transformed into related ketones by reaction with carbon nucleophilic agents such as Grignard reagents or organolithium reagents. This synthetic method is efficient to synthesize the asymmetric ketones. On the other hand, the cyano group can be used for cycloaddition reactions with other multiple bonds. For instance, alkyl nitriles are additionally cyclized with azides to give the tetrazoles. As introducing methods for the cyano group, the reaction of potassium cyanide with alkyl halides is a typical synthetic method and the copper cyanide-mediated Sandmeyer reaction and the Rosenmund-von Braun reaction have been known for a long time. Recently, cyanation reactions using palladium catalysts with some cyanating reagents have been developed. In addition, benzyl thiocyanate1), ethyl cyanoacetate2), tert-butyl isocyanide3) and acetone cyanohydrin4) play as cyanide ion sources and can be used for the direct cyanation of various substances.