The aza-Wittig reaction of iminophosphorane 3 with aromatic isocyanates gave carbodiimides 4, which were allowed to react further with various phenols and alcohols in the presence of a catalytic amount of solid potassium carbonate or sodium ethoxide to give 2-alkoxy(aryloxy)-benzofuro[3,2-d]pyrimidin- 4(3H)-ones in 72%～88% yields. Their structures were confirmed by 1H NMR, MS, IR and elemental analysis. The preliminary bioassays indicated that these compounds possessed moderate fungicidal activities against six kinds of fungi at a concentration of 50 mg/L.

Key words: benzofuro[3,2-d]pyrimidin-4(3H)-one, aza-Wittig reaction, carbodiimide, fungicidal activity