Intramolecular Diels-Alder chemistry of 4-vinylimidazoles

An investigation of 4-vinylimidazoles as diene components in the intramolecular Diels-Alder reaction is described. In the course of these studies several parameters affecting the cycloaddition were evaluated including the nature of the imidazole protecting group, the type of dienophile and the linking group. These investigations established that amino linkers were generally more effective than either ethers or esters. In most cases, the cycloadditions were highly stereoselective, resulting in the formation of products derived from an anti transition state. The polysubstituted tetrahydrobenzimidazole core of the pyrrole-imidazole alkaloid ageliferin can be constructed through the use of pseudo dimeric 4-vinylimidazoles.