4-{6-[6,11-bis-(tert-butyl-dimethyl-silanyloxy)-10-(4-methoxy-benzyloxy)-13-(4-methyl-3,6-dihydro-2H-pyran-2-yl)-4-methylene-trideca-7,12-dienyl]-5-methoxy-5,6-dihydro-2H-pyran-2-yl}-but-2-ynoic acid