Deflazacort Impurity 15

(6aR,6bS,7S,8aS,8bS,11aR,12aS,12bS) -7-hydroxy-8b- (2-methoxyacetyl) -6a,8a,10-trimethyl-1,2,6a,6b,7,8,8a,8b,11a,12,12a,12b-dodecahydro-4H-naphtho[2',1':4,5]indeno[1,2-d]oxazol-4-one