Reagents and solvents were purchased from commercial suppliers and used without further purification. Dialdehydes 1ad were synthesized by the well-knownVilsmeier-Haack for mylation. {5-[4-(diphenylamino)benzylidene]-4-oxo-2-thioxo-1,3-thiazolidin-3- yl}acetic acid(TPA-R)was synthesized according to
the earlier reported procedure