Use of tandem AN-AN reactions for the synthesis of thiazolo[4,5-e]-1,2,4-triazines

3-Aryl-1,2,4-triazines react with thioamides in acetic anhydride to produce thiazolo[4,5-e]-1,2,4-triazine derivatives and this reaction represents a new method for the fusion of thiazole and 1,2,4-triazine rings based on the nucleophilic ortho-diaddition type (A_N-A_N) cyclization reactions.