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 o-quinone 3-methyl-4,5-benzofurandione, , was prepared in 94% overall yield from p-henzoquinone and 1-morpholino-propene. The cycloaddition chemistry of with several dienes was examined and found to proceed in good to excellent yields. ... 3-Methyl-4,5-benzofurandione, , ...