1,3-dioxolane, 2-(2,4-cyclopentadien-1-ylidene)- 2-cyclopenta-2,4-dien-1-ylidene-1,3-dioxolane InChI=1/C8H8O2/c1-2-4-7(3-1)8-9-5-6-10-8/h1-4H,5-6H