Samarium diiodide promoted synthesis of N,N′-disubstituted amidines

An efficient one-step preparation of an N,N′-disubstituted amidine by the direct nucleophilic addition of an amine to the parent nitrile using catalytic amounts of SmI2 under relatively mild conditions is developed. Alkyl, benzyl and aryl amidines are prepared in moderate to good yields from the corresponding nitriles.