Bridgehead nitrogen heterocycles derived from the potassium salt of 2,3,5,6,7,8‐hexahydro‐3‐amino‐2‐thioxo benzothieno[2,3‐ d ]pyrimidin‐4‐(1 H )‐one

Derivatives of tetraheterocyclic linear system 2, 4 and 5 were prepared by reacting the potassium salt 1 with the appropriate alpha ‐halocarbonyl compounds. Moreover, through reaction of methyl mercapto 6 with hydrazine the new heterocyclic system 1,4,7,8,9,10‐hexahydro‐6 H ‐[1]benzothieno[2′,3′:4,5]pyrimido[1,2‐ b ]‐[1,2,4,5]tetrazin‐6‐one ( 8 ) was also obtained.