4-[(1S,2S)-3,3-Dimethyl-2-(3-methyl-but-3-enyl)-5-oxo-cyclopentyl]-3-oxo-butyric acid methyl ester

(Z)-4-[(1S,2S)-3,3-Dimethyl-2-(3-methyl-but-3-enyl)-5-oxo-cyclopentyl]-3-methoxy-but-2-enoic acid methyl ester