Absolute structure of (3aS,5S,7aS,7bS,9aR,10R,12aR,12bS )-7b-hydroxy- 4,4,7a,9a,12a-pentamethyl-10-[(2 R )-6-methylheptan-2-yl]- 2,8,9-trioxooctadecahydrobenzo[d ]indeno[4,5-b ]azepin-5-yl acetate from 62-year-old crystals