α-Naphthol synthesis via knoevenagel condensation in the presence of molecular sieves

Diphenylethanal condenses with diethyl malonate, ethyl acetoacetate, and ethyl benzoylacetate under Knoevenagel conditions in the presence of molecular sieves to give the 1-naphthols (2), (5), and (6). Glass wool is a less effective catalyst for formation of (2). 3,3-Diethoxycarbonyl-1,1-diphenylpropene (4) is converted into the naphthol (2) in high yield by heating with molecular sieves but its saturated analogue (3) is unaffected.