(6aR,7S,9aS,13aS)-5-Hydroxy-6a,7,10,10-tetramethyl-2,3,6,6a,7,8,9,9a,10,11,12,13-dodecahydro-1H-naphtho[1',8'a:5,6]pyrano[2,3-e]isoindol-3,11-dione