(1aR,2E,4aR,6S,7S,7aR,8S,9R,11aS)-1a,4a,5,6,7,7a,8,10,11,11a-Decahydro-4a,7,8-trihydroxy-1,1,3,6-tetramethylspiro[9H-cyclopenta[a]cyclopropa[f]cycloundecene-9,2'-oxiran]-4(1H)-one