<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Unsymmetrical thioureas, prepared in situ from isothiocyanates (I) and secondary amines (II), are oxidized by Cu(II) to the corresponding disulfide intermediates, which suffer an imine‐disulfide rearrangement to give thioamidoguanidines (III).</p> </abstract>