3-[6-(tert-butyl-dimethyl-silanyloxy)-10a-methyl-2-phenyl-octahydro-1,3,8,10-tetraoxa-anthracen-7-yl]-2-methyl-propionic acid 7-benzyloxy-6-(2-benzyloxy-ethyl)-2,6,8a-trimethyl-2-vinyl-octahydro-pyrano[3,2-b]pyran-3-yl ester