7,9-dioxo-8-oxa<4.4.4>propell-3-ene

12-bromo<4.4.3>propella-2,4,12-trien-11-one

(4aR,8aS)-8a-(2-Methoxycarbonyl-ethyl)-1,3,4,5,8,8a-hexahydro-2H-naphthalene-4a-carboxylic acid methyl ester

cis-9-(carboxymethyl)-Δ2-octalin-10-carboxylic acid

<4.4.3>propellan-11-one