[3-(tert-butyl-dimethylsilyl)oxy-2-carboxymethyl-5-oxo-cyclopentyl]acetic acid

[3-(tert-butyldimethylsilyl)oxy-2-methoxycabonylmethyl-5-oxocyclopentyl]acetic acid methyl ester

(3aS,4R,5S,6aR)-hexahydro-5-(tert-butyldimethylsilyl)oxy-4-(2-(2-nitrophenylselanyl)-ethyl)-cyclopenta[b]furan-2-one