(2S,4S,6R,8S,10S)-10-(tert-Butyl-dimethyl-silanyloxy)-8-(2-hydroxy-ethyl)-4-methyl-2-(2-triethylsilanyloxy-ethyl)-1,7-dioxa-spiro[5.5]undecan-4-ol

[(2R,4S,6S,8S,10S)-10-Methyl-8-((R)-3-methyl-2-methylene-4-triethylsilanyloxy-butyl)-4,10-bis-triethylsilanyloxy-1,7-dioxa-spiro[5.5]undec-2-yl]-acetic acid tert-butyl ester