(S)-1-[(2S,4S,6R,8R,10S)-8-Benzyloxymethyl-10-(tert-butyl-dimethyl-silanyloxy)-4-methoxy-1,7-dioxa-spiro[5.5]undec-2-yl]-3-[(4S,5R)-2-(3,4-dimethoxy-phenyl)-5-methyl-[1,3]dioxan-4-yl]-butan-2-one