Natural phosphate doped with potassium fluoride and modified with sodium nitrate: efficient catalysts for the Knoevenagel condensation

A high yield synthesis of activated alkenes is described using the inexpensive natural phosphate alone, doped with potassium fluoride or modified by sodium nitrate. The Knoevenagel condensation was carried out in mild conditions at room temperature in methanol. The catalytic activity of these phosphates are compared.