Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The thermal rearrangement of 2,5-dimethyl-3-isopropyl-4-isopropylidenehex-2-en-1,5-diyl to 4-isopropyl-3-isopropylidene-2,5-dimethylhexa-1,4-diene involves a 1,6-sigmatroplo shift of hydrogen which may occur in an antarafacial manner. ... From the reaction of acetyl ...