Rearrangement of Allyl Homoallyl Ethers to γ,δ-Unsaturated Carbonyl Compounds Catalyzed by Iridium Complexes

Abstract
Iridium complexes were found to promote the conversion of allyl homoallyl ethers to γ,δ-unsaturated carbonyl compounds. For example, treatment of 1-allyl-1-allyloxycyclohexane in the presence of catalytic amounts of [Ir(cod)Cl]2, PCy3, and Cs2CO3 in toluene at 100 °C afforded 4-cyclohexyliden-2,3-dimethylbutanal in 74% yield. The reaction presumably proceeds through double bond migration to allyl vinyl ethers, which then undergo the Claisen rearrangement.