SYNTHESIS OF PYRIDOPYRIMIDINE-2,4-DIONES FROM PYRIMIDO-1,2,4-TRIAZINE-6,8-DIONES BY REVERSED AZADIENE SYNTHESIS

Article abstract of DOI:10.1007/BF00499415

It as shown that pyrimido<4,5-e>-1,2,4-triazine-6,8-diones enter the reversed azadiene synthesis reaction with ketones and vinyl ethyl ether in the presence of diethylamine or boron trifluoride etherate, and also with enamines.As a result of the reaction, pyrido<2,3-d>pyrimidine-2,4-diones are formed in good yield.Pyrimido<5,4-e>-1,2,4-triazine-5,7-diones do not undergo such reactions with acetone.The reasons for the unique behavior of the isomeric pyrimidotriazinediones in the reaction with acetone are discussed.