(4aS.6aR.6bS.13aS.15aR.15bR)-methyl 2.2.6a.6b.9.9.13a-heptamethyl-15-oxo-1.2.3.4.4a.5.6.6a.6b.7.8.8a.9.13.13a.15.15a.15b-octadecahydropiceno[2.3-d]isoxazole-4a-carboxylate