Facile synthesis of S-arylisothioureas via the S-arylation of arylthioureas with aryl iodides in water

An environmentally benign, simple and highly efficient protocol for the synthesis of S-arylisothiourea derivatives has been achieved in good to excellent yields by reacting a series of aryl iodides with arylthioureas, using inexpensive CuSO₄·5H₂O as catalyst in water without PTC (phase transfer catalyst). The protocol features easy performance, good to excellent yields, good tolerance towards a variety of functional groups, which could be useful for the preparation of some biologically active compounds.