Synthesis of New Pyrimido[4,5‐e][1,2,4]triazolo[3,4‐b][1,3,4]thiadiazine Derivatives via S/N Smiles Rearrangement

Several new pyrimido[4,5‐e ][1,2,4]triazolo[3,4‐b ][1,3,4]thiadiazine derivatives ( 5a , 5b , 5c , 5d , 5e , 5f , 5g ) were synthesized through the condensation reaction of 5‐bromo‐4,6‐dichloropyrimidine ( 1 ) and 4‐amino‐5‐methyl‐4H‐1,2,4‐triazole‐3‐thiol ( 2 ). The single crystal X‐ray data of one of the derivatives confirmed the occurrence of the S/N type Smiles rearrangement during the course of the reaction.