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

tetrahydro-5',5'-dimethyl-3'-methylenespiro<1,3-dioxolane-2,2'(1'H)-pentalene>-3'a(3'H)-acetaldehyde

(2S,4aS,6aS,9aR)-octahydro-2-methoxy-8,8-dimethylpentaleno<1,6a-c>pyran-5(6H)-one

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