Leonotinin has been elucidated as 8 beta,17:9,13-diepoxy-labdane-16,15
: 19,6 beta-diolactone, [2aS-(2a alpha,5a beta,6 alpha 7 beta, 8a alph
a(8b anyl)ethyl]octahydro-6-hydroxy-2a,5a-dimethylspiro [2H-naphtho[1,
8-bc] furan-7(3H),2'-oxiran]-2-one, C20H26O5. The furan ring is exocyc
lic to the fused ring system. The three-membered oxirane ring is incli
ned at 67.4(5)degrees to the furan ring. The packing of the molecules
in the unit cell is purely the result of van der Waals interactions.