Reactivity and Selectivity in the Intermolecular Alder-Ene Reactions of Arynes with Functionalized Alkenes.

The reactivity and selectivity of functionalized alkenes in intermolecular Alder-ene reactions with arynes is described. The arynes generated from bis-1,3-diynes react with various trisubstituted and 1,1-disubstituted alkenes containing hydroxyl, amino, halo, carboxyl, boronate, and 1,3-dienyl functionalities, providing product distributions with varying degrees of selectivity between Alder-ene and addition reactions. The geometry of alkenes is another important factor for the reactivity of di- and trisubstituted alkenes where the allylic hydrogen of cis-disposed alkenyl system is reactive, which is the opposite reactivity compared to the corresponding intramolecular reaction.