New aromatic systems having a fused thiazolium ring

The method developed for the synthesis of thiazolo3,2-a]pyridinium salts has been extended to the first synthesis of simple thiazolo3,2-a]pyrimidinium, thiazolo3,2-a]-pyrazinium and thiazolo2, 3-b]benzod]thiazolium salts. No method could be found for the cyclization of 4′-bromo-2-(2-benzoxazolylthio)acetophenone to the thiazolo2,3-b]-benzoxazolium system.