6-{2'-ethyl-5'-[9-methoxy-7-(2-methoxy-3-methoxycarbonyl-1-methyl-butyl)-2,8-dimethyl-1,6-dioxa-spiro[4.5]dec-2-yl]-3-methyl-octahydro-[2,2']bifuranyl-5-yl}-2-methoxy-3,5-dimethyl-tetrahydro-pyran-2-carboxylic acid