(1S,9'R,10'R)-9',10'-dihydrospiro[cyclopentane-1,12'-[9,10]ethanoanthracen]-2-en-5-one

(2R,9'S,10'S)-9',10'-dihydro-6-oxaspiro[bicyclo[3.1.0]hexane-2,12'-[9,10]ethanoanthracen]-3-one

2-methyl-2-phenylsulfanylcyclopentane-1,3-dione

(9's,10's)-9',10'-dihydrospiro[cyclopentane-1,11'-[9,10]ethanoanthracen]-3-ene-2,5-dione

(1S,2S,9'R,10'R)-2-hydroxy-9',10'-dihydrospiro[cyclopentane-1,12'-[9,10]ethanoanthracen]-3-en-5-one