(3aR,5R,6aS,8S,10aR)-5-[(1S,2R,3R,4R,5R)-3-Bromo-2-methoxy-5-(4-methoxy-benzyloxy)-bicyclo[2.2.1]hept-2-yloxy]-8-(tert-butyl-dimethyl-silanyloxy)-4-methylene-octahydro-2-oxa-cyclopenta[d]naphthalen-3-one