4-[9-hydroxy-2-[5-[5-[6-hydroxy-3,5-dimethyl-6-(phenylcarbamoyloxymeth yl)oxan-2-yl]-3-methyl-oxolan-2-yl]-5-methyl-oxolan-2-yl]-2,8-dimethyl -1,6-dioxaspiro[4.5]dec-7-yl]-2-methyl-3-propanoyloxy-pentanoic acid