(1aS,3aS,4aS,5R,7aR,8aS,8bS)-7a,8b-dimethyl-5-(prop-1-en-2-yl)-1,1a,3a,4,4a,5,6,7,7a,8,8a,8b-dodecahydrocyclopenta[g]cyclopropa[a]naphthalene-3-carbaldehyde