Cyclization–oxidation of Benzylidenehydrazinecarbothioamides by FeCl3.6H2O or ZnCl2.6H2O Catalysts and Synthesis of New 1,3,4‐Thiadiazolo‐[3,2‐ α]Pyrimidines

We report new method for preparation of 2‐amino‐5‐aryl‐1,3,4‐thiadiazoles by reaction of arylaldehyde with thiosemicarbazide and in the next step via cyclization of 2‐aryl hydrazinecarbothioamide in the presence of ZnCl₂.6H₂O or FeCl₃.6H₂O. Also, in this research, new substituted 1,3,4‐thiadiazolo‐3,2‐α]pyrimidines were synthesized by the reaction of 2‐amino‐5‐aryl‐1,3,4‐thiadiazoles derivatives with DMAD or DEAD in the presence of K₂CO₃ under reflux conditions. The FT‐IR, ¹H‐NMR, ¹³C‐NMR, elemental analysis and single‐ crystal X‐ray analysis confirm the structures of the products.