Triamcinolone Hexacetonide Impurity B (Mixture of Diastereomers)

2-((6aS,6bR,7S,8aS,8bS,11aR,12aS,12bS)-6b-fluoro-7-hydroxy-6a,8a,10,10-tetramethyl-4-oxo-2,4,6a,6b,7,8,8a,8b,11a,12,12a,12b-dodecahydro-1H-naphtho[2′,1′:4,5]indeno[1,2-d][1,3]dioxol-8b-yl)-2-oxoethyl 3-methylbutanoate