4',5',6',6'a-tetrahydro-5',5'-dimethyl-3'-<(vinyloxy)methyl>spiro<1,3-dioxolane-2,2'(1'H)-pentalene>

((3aR,6aS)-2,2-Dimethyl-4-methylene-5-oxo-hexahydro-pentalen-3a-yl)-acetaldehyde

ethyl 2,3,3a,4,5,6-hexahydro-5,5-dimethyl-2-oxo-1-pentalenecarboxylate

4',5',6',6'a-tetrahydro-5',5'-dimethylspiro<1,3-dioxolane-2,2'(1H)-pentalene>-3'-methanol

4,4-dimethyl-2-(3'-carboethoxy-2'-oxo-propyl)-cyclopentanone