Conformations of carbocyclic ten-membered rings in some germacrane-type furan sesquiterpenes, linderalactone (1), litsealactone (3), a related ether (5), and a related dimethoxy-compound (9) in solution, have been determined by the used of intramolecular nuclear Overhauser effects. These conformations can readily explain the stereochemical aspects of the Cope rearrangements of these compounds and the stereochemistry of the products.