Synthesis of 9- and 10-membered rings by the intramolecular Michael addition of malonate on enone and ynone

The base-catalyzed (Cs2CO3 in THF/DMF) intramolecular Michael addition of β-ketoester-ynones 7–10 and -enone 11 is reported. Macrocyclization (Table 1), which produces the corresponding medium rings, was observed in 25–50% yield.