The Effect of Lewis Acids on the Intramolecular Diels-Alder Reaction of the Furan Diene

Abstract

Lewis acids have been found to accelerate the intramolecular Diels-Alder reaction of the furan diene in which the diene and dienophile are connected by four-carbon atoms [2-(4-oxo-5-alkenyl)furans]. The methodology has been extended to include acetylenic dienophiles [2-(1,1-dimethyl-4-oxo-5-alkynyl)furans], which cyclize to give the oxatricyclo ring system (5,6,7,8-tetrahydro-5,5-dimethyl-8-oxo-2H-2,4a-epoxynaphthalene).