3H-Furo[4,3,2-de]indeno[4,5-h]-2-benzopyran-9,11-dicarboxylicacid,1,6,6b,7,9a,10,11,11b-octahydro-1-(methoxymethyl)-9a,11b-dimethyl-3,6-dioxo-,dimethyl ester, [1S-(1a,6ba,9ab,11a,11bb)]-