2H,5H-Cyclopenta(d')naphtho(1,8-bc:2,3-b')difuran-6-acetic acid, 8-(3-furanyl)-2a,5a,6,6a,8,9,9a,10a,10b,10c-decahydro-2a,5a,6a,7-tetramethyl-5-oxo-, methyl ester, (2aR-(2aalpha,5aalpha,6alpha,6aalpha,8beta,9abeta,10alpha,10balpha,10c.beta))