6-[7-(3-benzyloxy-propyl)-8-(tert-butyl-dimethyl-silanyloxy)-3-(4-methoxy-benzyloxy)-8-methyl-decahydro-1,6-dioxa-heptalen-2-ylmethyl]-2-[3-(tert-butyl-diphenyl-silanyloxy)-propyl]-3,9a-dimethyl-octahydro-1,5-dioxa-benzocycloheptene-7,8-diol