Metal-Free Dehydrogenative Diels–Alder Reactions of Prenyl Derivatives with Dienophiles via a Thermal Reversible Process

An efficient dehydrogenative Diels–Alder reaction of prenyl derivatives with dienophiles has been developed. The reaction exhibits broad substrate scope and provides efficient access to cyclohexene derivatives with good to excellent yields. A reasonable mechanism involving a metal-free thermal reversible process is proposed.