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By using a gallium(III) triflate catalyzed intramolecular (4+3) cycloaddition, a few functionalized furan-derived tricycles that share the common guaianolide sesquiterpene ring system were prepared in a stereoselective manner in only three steps from commercially available starting materials. A discussion of the formation of alternative products is included, with possible substrate requirements to achieve the key cycloaddition step in an efficient way.