... Downloading zip file containing 3 articles... JavaScript is disabled on your browser. Please enable JavaScript to use all the features on this page. Tetrahedron. Volume 65, Issue 8, 21 February 2009, Pages 1689–1696. Cover image Cover image. Helical primary structures of 1,3-spiroannelated five-membered rings: (±)-trispiro[4.1.1.4.2.2] heptadecane and (±)-tetraspiro[4.1.1.1.4.2.2.2]heneicosane ☆. ...