The reactions of enaminones with dimethyl diazomalonate were investigated in the presence of copper(II) acetylacetonate. From the reaction of (E)-3-[methyl(phenyl)amino]-1-phenylprop-2-en-1-one (6c), dimethyl 2-[methyl(phenyl)amino]-4-oxonaphthalene-1,1-(4H)-dicarboxylate, was unexpectedly obtained as the major product. Quinoline derivatives were formed as the major products in the case of N-methyl-p-anisidino and N-methyl-p-toluidino enaminones. The reactions of acetyl enaminones were also realized, and quinoline derivatives were isolated as the major products. 3H- and 5H-dihydrofurans were also formed as side products in these reactions. These results differ from those reported earlier on the reactions of tertiary enaminones with carbenes/metal carbenes. © 2011 Verlag Helvetica Chimica Acta AG, Zürich, Switzerland.