Solvent-free Diels–Alder reactions of in situ generated cyclopentadiene

Abstract

A solvent-free Diels–Alder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile. Cyclopentadiene, formed in situ, reacted with the dienophile in a thermodynamically controlled reaction. Besides being solvent-free, the described procedure allows for almost complete utilization of dicyclopentadiene and avoids handling of noxious and hazardous cyclopentadiene. The reaction worked well with dienophiles such as maleic anhydride and unsaturated esters. However, unsaturated acids were not suitable dienophiles, yielding Diels–Alder adducts in a low yield.