[1S,2S,(+)]-9'α-Acetyloxy-4'b,8'aβ,9',10'-tetrahydro-3'β,10'β-dihydroxy-2,4'bα,7',8'-tetramethylspiro[cyclopropane-1,2'(1'H)-phenanthrene]-1',4',6'(3'H,5'H)-trione