Green synthesis of Guanidines directly from Thiourea

Abstract

In this work, one-pot synthesis of guanidines directly from isothiocyanates using DIB (diacetoxyiodobenzene) as a desulfurizing agent under a micellar condition in water was developed. The optimization study revealed that the use of 1wt%TPGS-750-M as a surfactant with NaOH as a base at room temperature can convert aromatic isothiocyanates and varieties of amines into the corresponding guanidines in good to excellent yields (69 - 95%). This green synthetic process in water can be applied to prepare guanidine at gram-scale quantity. The aqueous micellar medium was also reusable to give relatively the similar reaction yields for at least three cycles. The key benefit of this reaction is metal-free, utilize water as a solvent and operate at room temperature in an open flask. Moreover, the synthetic methodology was also applied to prepare as NC-174 sweetener, pinacidil drug, and biodiesel catalyst