Platinum(II)/europium(III)-catalyzed intramolecular hydroalkylation of 4-pentenyl β-dicarbonyl compounds

Reaction of 5,5-dimethyl-8-nonene-2,4-dione with a catalytic mixture of [PtCl2(CH2CH2)]2 (2) (1 mol %), and EuCl3 (2 mol %) in dioxane that contained HCl (1.0 equiv) at 90 °C for 18 h led to the isolation of 2-acetyl-3,6,6-trimethyl-2-cyclohexanone in 85% yield. A number of 4-pentenyl β-dicarbonyl compounds underwent intramolecular hydroalkylation to form cyclohexanones in moderate to excellent yield.