Conjugate addition reactions of 2,4-pentandione, dibenzoylmethane and ethylacetoacetate to enones have been investigated using Amberlyst-15 or Amberlyst-15-DMAP acetate system as catalysts. When 2,4-pentandione reactions were carried out in the presence of Amberlyst-15, conjugate addition and/or conjugate -addition initiated ring closure products were obtained depending on the reaction conditions. However, unlike 2,4-pentandione, dibenzoylmethane gave only conjugate addition products with Amberlyst-15. When Amberlyst-15-DMAP acetate system was used, always only conjugate addition products were obtained with beta-dicarbonyl compounds independent of the reaction conditions. (C) 2017 Elsevier Ltd. All rights reserved.