(3aR,4aS,5aR,7S,8S,9R,9aR,10aR,12S,12aS)-8,9-Bis-benzyloxy-12-iodo-7-(2-methyl-[1,3]dithian-2-ylmethyl)-12-triethylsilanyl-dodecahydro-1,4,6,10-tetraoxa-naphtho[2,3-f]azulen-2-one