Ultrasound-assisted synthesis of substituted guanidines using 1H-pyrazole-1-carboxamidine and S-methylisothiouronium sulfate under solvent-free conditions

Abstract We have investigated ultrasound-assisted synthesis of guanidine derivatives using 1 H -Pyrazole-1-carboxamidine (PyzCA) and S-substituted isothiouronium sulfate (MeITU). The guanylations of several amines are promoted by ultrasound sonication under solvent-free conditions, and proceed under mild conditions. It is of particular interest that the guanylations do not require bases in most cases.