Further studies on the ring transformation of pyrimido [5, 4-e]-as-triazine 4-oxides to pyrrolo [3, 2-d] pyrimidines involving 1, 3-dipolar cycloaddition reaction
The reaction of 3-alkyl (or aryl)-6, 8-dimethylppimido [5, 4-e]-as-triazine-5, 7 (6H, 8H)-dione 4-oxides (la-f) with ethyl phenylpropiolate (EPP) in toluene afforded the unexpected 6-alkyl (or aryl)-5-benzoyl-7-(ethoxycarbonyl)-1, 3-dimethylpyrrolo [3, 2-d] pyrimidine-2, 4 (lH, BH)- dioneS (7a-f). The structures of 7a-f were supported by the spectral data as well as by the chemical means and were confirmed by the single-crystal X-ray diffractions. On the other ...