Reaction of N-substituted 3,4-dichloromaleimides with alpha-mercaptoazaheterocycles

Reaction of N-substituted 3,4-dichloromaleimides (1) with alpha -mercaptoaz aheterocycles, 2-mercapto-1H-benzo[d]imidazole (2) and 3-thioxo-2,3,4,5-tet rahydro- 1,2,4-triazin-5-ones (4) in the presence of triethylamine, led to the formation of condensed thiazole ring resulting in 2,3-dihydro-1Hbenzo[4 ,5]imidazo[2,1-b]pyrrolo[3,4-d][1,3]thiazole-1,3-diones (5) and 7,8-dihydro -2H,6H-pyrrolo[3',4':4,5][1,3]thiazolo[3,2-b][1,2,4]triazine-2,6,-S-triones (8), respectively. Refluxing of 8 in aqueous dioxane-triethylamine produce d derivatives of 7-oxo-7H-[1,3]thiazolo[3,2-b][1,2,4]triazine-2-carboxarnid es (9) by destruction of maleimide ring with decarboxylation. The structure of 9i was confirmed by X-Ray analysis. 1 reacted with 2-thioxo-1,2,3,4-tet rahydro-4quinazolinone (3) with cyclization at N-1 and N-3 positions.