2-Cyclopentene-1-carboxylicacid,5-[(decahydro-1,2,4a-trimethyl-5-methylene-1-naphthalenyl)methyl]-1-hydroxy-3-methoxy-4-oxo-,methyl ester, [1R-[1a(1R*,5S*),2b,4ab,8aa]]-