(1R,5S)-5-methyl-bicyclo<3.3.0>octan-3-one

(1R,2R,5R,7R)-2-(trimethylsilyl)-7-(tert-butyldimethylsilyloxy)bicyclo[3.3.0]-octan-3-one

(1R,5S,7R)-1-methyl-7-(tert-butyldimethylsilyloxy)bicyclo[3.3.0]oct-2-ene

(3aR,5R,6aR)-5-(tert-Butyl-dimethyl-silanyloxy)-3a-(3-hydroxy-1-methylene-propyl)-hexahydro-pentalen-2-one

(1R,5R,7R)-7-(tert-butyldimethylsilyloxy)-1-[4-(1-ethoxyethyloxy)but-1-en-2-yl]bicyclo[3.3.0]octan-3-one