(2R,2aS,4S,4aR,5R,6R,7R,7aS,7bR)-2-acetoxy-5-tert-butyldimethylsiloxy-4-[1-acetoxy[4-methoxy-3-(methoxymethoxy)phenyl]methyl]-6,7-(isopropylidenedioxy)decahydroindeno[7,1-bc]furan