1-Octene-3,5-dione,7-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-1-[(2R,3R)-3-[2-[(2R,3R)-3-[[[(1,1-dimethylethyl)dimethylsilyl]oxy]methyl]-2-methyloxiranyl]ethyl]-2-methyloxiranyl]-4-methyl-, (1E,4S,7R)-