Homonuclear Diels-Alder dimerization of 5-ethenyl-2-phenylsulfanyl-1H-imidazoles and its application to synthesis of 12,12′-dimethylageliferin

Homonuclear Diels-Alder dimerization of various 5-ethenyl-2-phenylsulfanyl-1H-imidazoles provided a novel highly regio- and stereoselective route to the preparation of multifunctionalized 4,5,6,7-tetrahydrobenzimidazoles, which is the basic skeleton of ageliferin, a biologically active pyrrole-imidazole marine alkaloid. The reaction was applied to the synthesis of 12,12'-dimethylageliferin. (c) 2006 Elsevier Ltd. All rights reserved.