tert-butyl(2-((2S,3S,5R,7R,9R,10S,11R,15S)-10-chloro-11-methoxy-15-methyl-3-((triethylsilyl)oxy)-9-vinyl-1,6,8-trioxadispiro[4.1.57.35]pentadecan-2-yl)ethoxy)dimethylsilane