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 conversion of the (Z)-epoxyhexenynes / into three pairs of isomeric vinylfuran derivatives is explained on the basis of a multi-step mechanism with butenynyl carbonyl ylides, cycloallenes and vinyl carbenes as intermediates. ... Suggested intermediates are: butenyl carbonyl ...