Azines and Azoles: CXXVI.~1 First Example of a Novel Heterocyclic System: Pyrimido[1,6-a][1,5]benzodiazepines

摘要

4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones readily undergo acylation at the N~1 atom of the benzodiazepine system by the action of acetic anhydride.Heating of the acetylated products in boiling dimethylforrnamide leads to the formation of 75-93% of the corresponding 7-acetyl-6-R-6,7-dihydropyrimido[1,6-a][1,5]benzodiazepine-1,3-diones that are derivatives of hitherto unknown fused heterocyclic system,pyrimido[1,6-a][1,5]benzodiazepine.4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones are converted into 1-(2-aminophenyl)-6-(2-R-vinyl)uracils on heating in boiling DMF.