(1aR)-8β-Acetyloxy-1,1aα,1bβ,1cα,2a,3,3a,6aα,6b,7,8,8a-dodecahydro-3aβ,6bα,8aα-trihydroxy-2aα-hydroxymethyl-1,1,5,7α-tetramethyl-4H-cyclopropa[5,6]benz[1,2:7,8]azuleno[5,6-b]oxiren-4-one