... Please enable JavaScript to use all the features on this page. Tetrahedron Letters. Volume 50, Issue 14, 8 April 2009, Pages 1607–1609. Cover image Cover image. ... 50%), the (Z,E) isomer (ca. 40%) and the (E,E) isomer (4%), contaminated with about 6% of 1,6-bis(trimethylsilyl)-2,