[摘要]：A new route to substituted pyrimido[5,4-e]-1,2,4-triazine-5,7(1H,6H)-diones is outlined. The synthesis proceeds via preformed hydrazone intermediates, which are then condensed with all activated chlorouracil to build up the entire molecular framework, followed by a reductive ring closure to provide the parent series. The route has been extended to the isomeric pyrimido[5,4-e]-1,2,4-triazine-5,7(6H,8H)-dione class via the use of methylhydrazine as hydrazine surrogate, followed by regiospecific alkylation of the N-8-H pyrimidotriazinediones with a range of alkyl and alkaryl substituents. This new methodology permits the generation of a wide range of compounds with variable substitution at the N-1, C-3, and N-8 positions for a heterocyclic scaffold with demonstrated pharmacological activity.
