Intramolecular Diels-Alder reactions of 4-vinylimidazoles.
[reaction: see text] The synthesis of a variety of unsaturated ethers, esters, and amides derived from urocanic acid and their Diels-Alder reactions are reported. Propargylic ethers and esters cyclize with reasonable efficiencies, but the related mono- and unactivated olefins did not cyclize. On the other hand, the corresponding amines and amides, along with the doubly activated ester/amide derivatives participate in the cycloaddition reaction.