(3R,4S)-3-Hydroxy-4-[(2S,3R)-5-methoxy-3-((R)-2-methyl-3-oxo-butyl)-tetrahydro-furan-2-yl]-pentanoic acid methyl ester

(7E,9E)-(2S,3aR,5R,6S,11R,12R,16R,17S,17aS)-12-Ethyl-6,16-dihydroxy-2-methoxy-5,9,17-trimethyl-11-trityloxymethyl-2,3,3a,4,5,6,11,12,15,16,17,17a-dodecahydro-1,13-dioxa-cyclopentacyclohexadecen-14-one