Applications of a novel carbon-nitrogen bond cleavage reaction (part-I). A new synthesis/derivatisation of 5H-indeno[1,2 d] pyrimidines and pyrimido[6,1-a]isoindoles

Article abstract of DOI:10.1016/S0040-4020(01)80524-X

Substituted 6-(4,5-dimethoxy-2-vinylphenyl)-2,4-(1H, 3H) pyrimidinediones (2) undergo ring closure in the presence of a mixture of formic acid and orthophosphoric acid, to give 5H-indeno[1,2-d]pyrimidines (3) and/or pyrimido[6,1-a]isoindoles (4). Cyclizat