“…Recently, unsaturated 1,4-dicarbonyl compounds, such as 1,4-ketoesters [6–8], 1,4-diketones [9], 1,4-ketoamides [9–10] and dialkylfumarates [11], have been the substrates for this reaction. The reaction products can undergo further chemical transformations, allowing the possibility of cascade reactions, making the method attractive for the synthesis of several valuable compounds, such as drugs and natural products.…”