(4aR,5aR,6aR,10aS,11aR,12aS)-5a,11a-Dimethoxy-tetradecahydro-1,5,7,11-tetraoxa-naphthacene

1-[(2R,3S)-3-(tert-Butyl-dimethyl-silanyloxy)-tetrahydro-pyran-2-yl]-4-[(2S,3R)-3-(tert-butyl-dimethyl-silanyloxy)-tetrahydro-pyran-2-yl]-butane-2,3-dione