(1aS-(1a alpha,1b beta,2 beta,5 beta,6 alpha,6a beta,7 beta,7a alpha,8S*))-hexahydro-1b,6-dihydroxy- 6a-methyl-8-(1-methylethenyl)spiro(2,5-methano-7H- oxireno(3,4)cyclopent(1,2-d)oxepin-7,2'-oxiran)- 3(2 alpha H)-one