One-Pot Synthesis of C<inf>2</inf>Symmetric and Asymmetric N,N′,N″-Substituted Guanidines from Aryl Isothiocyanates and Amines

Abstract

© Georg Thieme Verlag. Highly substituted guanidines were conveniently prepared through a one-pot reaction between aryl isothiocyanates and amines mediated by the Ph3P-I2/Et3N system. The C2-symmetric N,N′,N″-substituted guanidines were readily accessed using a 1:2 molar ratio of an aryl isothiocyanate and an amine; while sequential addition of two different amines in equimolar ratios gave rise to asymmetric derivatives. Both primary and secondary amines were found to react preferentially with electron-deficient aryl isothiocyanates, rapidly providing guanidines in good yields under mild conditions.