Benzoic acid (1S,2S,3S,4S,5S,9S)-5-acetoxy-3-((R)-2-benzyloxymethoxy-1-methylene-pent-4-enyl)-1-hydroxy-4,8,11,11-tetramethyl-6-oxo-9-triisopropylsilanyloxy-bicyclo[5.3.1]undec-7-en-2-yl ester