Acetic acid (2S,5R,7S,9S,10S,12R,15R)-2-((2R,5R,6S)-5-ethyl-6-methyl-5-triethylsilanyloxy-tetrahydro-pyran-2-yl)-9-((R)-1-ethyl-2-oxo-butyl)-2,10,12-trimethyl-1,6,8-trioxa-dispiro[4.1.5.3]pentadec-13-en-15-yl ester

(2S,5S,7S,9S,10S,12R,15R)-2-((2R,5R,6S)-5-ethyl-6-methyl-5-((triethylsilyl)oxy)tetrahydro-2H-pyran-2-yl)-2,10,12-trimethyl-9-((R)-4-oxohexan-3-yl)-1,6,8-trioxadispiro[4.1.57.35]pentadec-13-en-15-yl acetate