a-Bromoacyl chlorides, functioning as 1, 2-bielectrophiles, undergo ready reaction in the presence of Et3N with several monoprotonic 1, d-binucleophiles to provide an especially convenient synthesis of some five-membered mesoionic ring systems containing diverse functional substituents. The anhydro-4-hydroxythiazolium hydroxide system results from N- monosubstituted thioamide derivatives, the anhydro-4-hydroxy-l, 3-dithiolium hydroxide ...