Synthesis of Pyrido[4, 3-d]pyrimidin-5(6H)-ones via Anionic Cycloaddition of Methyl 2, 4-Dimethoxy-6-methyl-5-pyrimidinecarboxylate with Imines

抄録

A new route is described for the synthesis of pyrido[4, 3-d]pyrimidin-5(6H)-ones. Treatment of methl 2, 4-dimethoxy-6-methyl-5-pyrimidinecarboxylate with lithium diisopropylamine in tetrahydrofuran at -70°C under nitrogen followed by reaction with diaryl imines afforded cycloaddition products. The cycloadducts were aromatized to the corresponding pyrido[3, 4-d]pyrimidin-5(6H)-ones by treatment with N-bromosuccinimide via a benzylic bromination-dehydrobromination sequence.