[Br:1][C:2]1[C:3](=[O:9])[NH:4][C:5](=[O:8])[NH:6][N:7]=1.O=C1N[C:15](=[O:17])[CH:14]=NN1>C(OC(=O)C)(=O)C>[C:15]([N:6]1[C:5](=[O:8])[NH:4][C:3](=[O:9])[C:2]([Br:1])=[N:7]1)(=[O:17])[CH3:14]The 6-bromo-3,5-dioxo-(2H,4H)-1,2,4-triazine (5 g) obtained from the 3,5-dioxo-(2H,4H)-1,2,4-triazine in accordance with the technique described in example 1b is treated with acetic anhydride (50 ml) for 7 hours under reflux. After concentration to dryness under vacuum and taking up in ethyl ether, the precipitate is filtered, centrifuged, and dried under vacuum at 50° C. to give compound 15a (4.6 g).
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