(4E,6E)-(2R,3S)-8-[(2R,3S,6S,8S,9R)-9-Butyl-9-(tert-butyl-dimethyl-silanyloxy)-8-ethynyl-3-methyl-1,7-dioxa-spiro[5.5]undec-2-yl]-3-hydroxy-1-((S)-4-isopropyl-2-thioxo-oxazolidin-3-yl)-2,6-dimethyl-octa-4,6-dien-1-one