(1R,2S,3R)-1-[(4-methoxybenzyloxy)methyl]-2,3-bis(4-methoxybenzyloxy)-4-(tert-butyldimethylsiloxy)butyl (2E,4R,5R,6E)-2,4,6-trimethyl-5-(triphenylsiloxy)-7-iodo-2,6-heptadienoate