(2R,5R,6S)-5-Benzyloxy-6-(2-benzyloxy-ethyl)-2-[(2R,4aR,6S,7S,9aS)-7-(4-methoxy-benzyloxy)-2-phenyl-hexahydro-1,3,5-trioxa-benzocyclohepten-6-ylmethyl]-dihydro-pyran-3-one