The effect of microwave irradiation on Michael addition of β-dicarbonyl compounds (acetylacetone, methyl acetoacetate, dimethyl malonate and diethyl ethylmalonate) to methyl vinyl ketone was investigated by using six different metal acetylacetonate catalysts, i. e., Cr (acac)3, Mn (acac)2, Fe (acac)3, Co (acac)2, Ni (acac)2 and Cu (acac)2 without any solvent.
The microwave irradiation markedly accelerated the addition reaction, reducing the reaction time dramatically in comparison with the case of mechanical stirring (1/100 1/1400). The yields of the products were also moderately improved, and the values of the yield were dependent on the metal acetylacetonate catalysts. Thus, the order was well correlated with the electronegativity of the metal cation of the metal acetylacetonate catalysts.