6-Polyfluoroalkylated 2-thiouracils in the synthesis of pyrimido[2,1-b][1,3,5]thiadiazines by the double Mannich reaction

6-Polyfluoroalkyl-2-thiouracils react with formaldehyde and primary amines in EtOH (MeCN) at 2-mercapto and 3-amino groups to yield pyrimido[2,1-b][1,3,5]thiadiazines via the multicomponent double Mannich reaction. The structure of 3-benzyl-8-nonafluorobutyl-3,4-dihydro-2H,6H-pyrimido[2,1-b][1,3,5]thiadiazin-6-one was studied by the X-ray diffraction analysis. The use of ethylenediamine in these reactions yields 3,3′-ethane-1,2-diyl-bis(pyrimido[2,1-b]thiadiazinone) as a result of the bis-double Mannich cyclocondensation. 8-Polyfluoroalkyl-pyrimido[2,1-b]thiadiazines exhibit weak tuberculostatic activity.