A simple, environmentally friendly, tandem Knoevenagel condensation and Michael addition procedure is reported. The reactions between cyclic-13-diketones and a variety of aldehydes were carried out in water to afford tetraketones (64–99%). In this green synthetic protocol, the solvent water itself catalysed the reaction by hydrogen bonding, thus avoiding the use of any other catalysts to make the work up procedure easier.
A green and highly efficient synthesis of 5,5-(phenylmethylene)bis(1,3-dioxane-4,6-dione) derivatives through tandem Knoevenagel condensation and Michael addition of aromatic aldehydes and 1,3-dioxane-4,6-dione in gluconic acid aqueous solution (GAAS) is described. Gluconic acid aqueous solution could be recycled and reused several times without significant loss of its effciency.