Tandem AN–AN reactions in the synthesis of tetrahydrothiazolo[4,5-e][1,2,4]triazines

Reaction of 3-aryl-1,2,4-triazines with S,N-dinucleophilic N-(het)arylthioureas in acetic anhydride at room temperature affords the cyclization products, tetrahydrothiazolo[4,5-e]-[1,2,4]triazines in good yields. The structure of the heterocyclic system thus formed was confirmed by X-ray diffraction analysis.