Diels–Alder intramolecular cycloaddition of vinylallenyl cycloalken-3-yl ethers

Abstract

Cohalogenation of cycloalkenes 1 by N-bromosuccinimide (NBS) in 4-methylpent-4-en-2-yn-1-ol affords β-bromopent-4-en-2-ynyl ethers 2 which undergo facile base-promoted consecutive dehydrohalogenation-isomerization-intramolecular Diels–Alder cycloaddition leading to tricyclic conjugated enol ethers 6.