A facile synthesis and fungicidal activities of novel fluorine-containing pyrido[4,3-d]pyrimidin-4(3H)-ones

Sixteen novel 2-substituted-pyrido[4,3-d]pyrimidin-4(3H)-ones 5a-5p were easily synthesized via tandem aza-Wittig and annulation reactions. Their structures were clearly verified by IR, 1H NMR, EI-MS spectroscopy and elemental analysis, and 5a, analyzed by single-crystal X-ray diffraction. The results of preliminary bioassay indicated that some compounds possess significant fungicidal activities.