(2R,3S,4S,5S,7S,10S,12S,13Z)-11-(tert-butyldimethylsilanyloxy)-3,5-[(R)-4-methoxybenzylidenedioxy]-7-methoxymethoxy-2,4,10,12-tetramethyl-14-trimethylsilanylpentadeca-13-en-8-yn acid methyl ester