Metallic Nickel Assisted Room-Temperature Generation and Diels-Alder Chemistry of o-Xylylene Intermediates

Article abstract of DOI:10.1021/jo00237a022

Highly reactive metallic nickel, prepared by the lithium metal reduction of nickel iodide using naphthalene as an electron carrier, was found to induce 1,4-dehalogenation of α,α'-dihalo-o-xylene derivatives at room temperature.The reaction proceeds in the presence of a variety of electron-deficient olefins, giving Diels-Alder cycloadducts in moderate to good yields presumably via the highly reactive intermediate o-xylylene 2. 1,3-Dibromoindan and 1,4-dibromo-1,2,3,4-tetrahydronaphthalene also react in the presence of electron-deficient olefins to give bridged cycloadducts in moderate yields.Methoxy as well as electron-deficient substituents such as bromide and nitrile groups on the aromatic ring of the starting dibromide were shown to be compatible with the reaction conditions yielding substituted cycloadducts in good yields.