Ethyl 1-methyl-2-(1-methylallylidene)-cyclopentane-1-acetate

Ethyl 1-methyl-2-(1-methyl-3-trimethylsilyl-2-propyn-1-ylidene)-cyclopentane-1-acetate

(4β,8α)-1α,4β-Dimethyl-9-carbethoxytricyclo<6.3.0.04,8>undec-9-en-2-one