Acetic acid (3aR,4S,6aR,8S,10aR)-4-methyl-3,5-dioxo-4-((1R,2R,4S,6R)-3-oxo-6-phenyl-bicyclo[2.2.1]hept-2-yl)-decahydro-2-oxa-cyclopenta[d]naphthalen-8-yl ester

(3aS,6aS,8S,10aR)-8-(tert-Butyl-dimethyl-silanyloxy)-4-methylene-octahydro-2-oxa-cyclopenta[d]naphthalen-3-one

(3aR,6aS,8S,10aR)-8-(tert-Butyl-dimethyl-silanyloxy)-hexahydro-2-oxa-cyclopenta[d]naphthalene-3,4-dione

(3aR,5R,6aS,8S,10aR)-8-(tert-Butyl-dimethyl-silanyloxy)-5-hydroxy-4-methylene-octahydro-2-oxa-cyclopenta[d]naphthalen-3-one