Double dehydro-diels-alder reactions of 1,5-dien-3-ynes

A study was conducted to demonstrate double dehydro-diels-alder reactions of 1,5-dien-3-ynes. It was demonstrated that the reaction proceeded through two concerted cycloadditions, the first of which was proposed to be reversible. Detailed analysis revealed some of general features of the unique double diels-alder reaction. The reaction proceeded at only at high temperature, the dienophile needed to be highly activated, and yields were always low. N-Methylmaleimide (NMM) and 1,2-dicyclohexenyl acetylene 1 were selected as representative reaction partners to conduct the optimization investigations. Some of the parameters that were varied during the course of the reaction, included temperature, method of heating, and reaction stoichiometry. The effects of various radical inhibitors, solvents, and treated glassware were also investigated under the study.