7,9a-Methano-9aH-cyclopenta(b)heptalene-2,4,8,11,11a,12(1H)-hexol, dodecahydro-1,1,4,8-tetramethyl-, 12-butyrate, (2S,3as,4R,4ar,7R,8R,9as,11R,11aR,12R)-