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 conversion of substituted 2-hydroxy-1,4-benzoquinones, 1, to 2-cyclopentene-1,4-diones , 3, is effected by thermolysis of their iodonium zwitterions, 2. Some cycloadditions through 2 are also described. ... All cyclopentenediones 3, with the exception of 3d, have been ...