(αR,βS)-β-(BenzoylaMino)-α-tert-butyl(diMethyl)silyloxy-benzenepropanoic Acid (2aR,4S,4aS,6R,9S,11S,12S,12aR,12bS)-6,12b-Bis(acetyloxy)-2a,3,4,4a,5,6,9,10,11,12,12a,12b-dodecahydro-4-triethylsilyloxy-11-hydroxy-4a,8,13,13-tetraMethyl-5-oxo-12-[(1-oxopenty [ 1055033-93-6 ]