Spiro[dicyclopenta[a,d]cyclooctene-3(2H),2′(3’H)- furan]-6-carboxaldehyde,1,3a,4,4′,5′,6a,7,9a,- 10,10a-decahydro-3′,9,10a-trimethyl-5′-(2- methyl-1-propenyl)-7-oxo-,(2’S,3’S,3aR,5’R,- 6aS,9aS,10aR)-