“…trans,trans-2,7-Dimethyl-l,3,5,7-octatetraene exhibits a clean NMR spectra consistent with the assigned structure, as well as ir and uv data almost identical with those of trans,trans-1,3,5,7-octatetraene. 15 NMR examination of the dienediyne showed a very clean spectra consistent with the assigned structure and suggestive of only one product. Since hydroboration of 2,4hexadiyne gives the cis vinylborane, the mercurial dimerization product is presumably (£,E)-4,5-diethylidene-2,6-octadiyne.…”