One‐pot Synthesis of Novel 2,8‐dithioxopyrano[2,3‐d:6,5‐d′]dipyrimidine‐4,6(1 H )‐dione Catalyzed by p ‐Toluenesulfonic Acid

Novel 2,8‐dithioxopyrano[2,3‐d:6,5‐d′]dipyrimidine‐4,6(1 H )‐dione derivatives were synthesized by a clean and efficient methodologies involving one‐pot regioselective and chemoselective reactions between two moles substituted thiobarbituric acid and 1 mol various aromatic aldehydes in the presence of p ‐toluenesulfonic acid as a catalyst in EtOH with good yields in compression with alternative conditions such as microwave and promoted ultrasound. All of the compounds have been characterized by IR, 1 H NMR, 13 C NMR spectral data, and elemental analyses.