Abstract Heptadienes containing nucleic bases are attractive building blocks for the synthesis of carbocyclic oligonucleotide analogs. Herein, we report an alternative synthetic route to 4??[(1H, 3H)??pyrimidine??2, 4??dion??1??yl]??1, 6??heptadiene and 4??[(1H, 3H)??5?? methylpyrimidine??2, 4??dion??1??yl]??1, 6??heptadiene via building the pyrimidine ring utilizing 4?? isocyanato??1, 6??heptadiene intermediate.