(3R,4S)-3-Hydroxy-4-[(2S,3R)-3-((4E,6E)-(2S,8R,9S)-9-hydroxy-2,6-dimethyl-3-oxo-8-trityloxymethyl-undeca-4,6-dienyl)-5-methoxy-tetrahydro-furan-2-yl]-pentanoic acid methyl ester