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Abstract
Ethyl 2-methyl-11-oxo-9, 10-dihydro-1 H , 11 H -pyrido[4",3":4',5']thieno[2',3':4,5]pyrimido[2,1-b][1,3,4]thiadiazine-8(7 H )-carboxylate 7 has been synthesised by the reaction of ethyl 3-amino-4-oxo-2-thioxo-1,3,4,5,6,8-hexahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidine-7(2 H )-carboxylate 2 with allylbromide followed by treatment with bromine and subsequent dehydrobromination of the brominated product 5 with ethanolic sodium hydroxide. Its isomeric ethyl 2-methyl-11-oxo-9,10-dihydro-3 H ,11 H -pyrido[4",3Prime;:4',5']thieno[2',3':4,5]pyrimido[2,1-b][1,3,4]thiadiazine-8(7 H )-carboxylate 8 has been obtained by condensation of 2 with chloroacetone followed by cyclization of the intermediate 9 with p -toulenesulfonic acid. The thiadiazino derivatives 11 , 13 , 15 were prepared through the reaction of 2 with the appropriate f -halocarbonyl compounds followed by cyclization reactions of the intermediates 10 , 12 , 14 .