2,5α,8β-Trimethyl-6-oxo-(1α,5α)-tricyclo<6.3.0.01.5>undec-2-ene

4-(2-methylcyclopenten-3-ylidene)-1-trimethylsilyl-1-butyne

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

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

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