A simple and efficient procedure for the synthesis of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives has been developed via one-pot three-component reaction of 2-naphthol, aldehydes, and dimedone in the presence of ammonium oxalate as a mild and inexpensive catalyst under solvent-free conditions. The present method is operationally simple and offers several advantages such as high yields, short reaction time, economic availability of the catalyst, and simple workup.