Synthesis and biological activity of oxindolylidene derivatives of imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazin-7-ones and imidazo[4,5-e]thiazolo[2,3-N]-1,2,4-triazin-8-ones

Reactions of 1,3-dialkyl-2-thioxo-1,2,3,3a,9,9a-hexahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazin-7(6H)-ones with isatin and its derivatives under base catalysis conditions lead to the corresponding 1,3-dialkyl-6(7)-(2-oxoindolin-3-ylidene)derivatives of 2-thioxo-1,2,3,3a,9,9a-hexahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazin-7(6H)-one or 2-thioxo-1,2,3,3a,4,9a-hexahydroimidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazin-8(7H)-one resulting from the aldol-crotonic condensation and skeletal amidine rearrangement of the thiazolotriazine fragment, depending on the amount of added alkali.