US6080826A, original inventors Robert H. Grubbs, Michael J. Marsella and Heather D. Maynard. Table 1 reports template effects on cyclic-polyether formation; the discussion explicitly identifies a 14-membered ring. Only the nonbiological chemical evidence is used here.
Primary chemical study of lithium-templated ring-closing metathesis and related unsaturated polyether formation, Angewandte Chemie International Edition in English 36, 1101–1103.