(2R,6S,8R)-8-((S)-2-Benzyloxy-1-methyl-ethyl)-10-(tert-butyl-dimethyl-silanyloxy)-2-vinyl-1,7-dioxa-spiro[5.5]undecan-4-one

[(2R,6R,8R,10S)-10-Benzyloxy-2-((S)-2-benzyloxy-1-methyl-ethyl)-8-vinyl-1,7-dioxa-spiro[5.5]undec-4-yloxy]-tert-butyl-dimethyl-silane

[(2R,4R,6R,8R,10S)-10-Benzyloxy-2-((S)-2-benzyloxy-1-methyl-ethyl)-8-vinyl-1,7-dioxa-spiro[5.5]undec-4-yloxy]-triisopropyl-silane