(E)-4-[(E)-Methoxyimino]-but-2-enoic acid {(E)-3-[(1S,11S,13S,15R)-7,15-bis-(tert-butyl-dimethyl-silanyloxy)-9-oxo-10,17-dioxa-tricyclo[11.3.1.03,8]heptadeca-3(8),4,6-trien-11-yl]-propenyl}-amide