Flavanones were synthesized via a series reaction scheme involving the Claisen–Schmidt condensation of 2′-hydroxyacetophenone and benzaldehydes to form 2′-hydroxychalcones, and the subsequent isomerization of the 2′-hydroxychalcones to flavanones. Reactions were carried out at 160 °C heterogeneously using MgO as the catalyst. Substitution effects were investigated by conducting reaction studies involving various para-substituted benzaldehydes (i.e., OH, OCH3, H, F, Cl, Br and NO2). Different solvents, including DMSO, nitrobenzene, benzonitrile and tetralin, were used. The results from this work suggest that a negatively charged ketone intermediate, similar to one previously proposed for the homogeneously base-catalyzed reaction, is also involved in the heterogeneous synthesis under these conditions. [Copyright &y& Elsevier]