1-[[5-[[2-(Carboxymethyl)-3-[[decahydro-5-(hydroxymethyl)-5,8a-dimethyl-2-methylene-1-naphthalenyl]methoxy]-4-methoxy-1,4-dioxobutoxy]methyl]decahydro-5,8a-dimethyl-2-methylene-1-naphthalenyl]methoxy]-1,2,3-propanetricarboxylic Acid, 1,2-Dimethyl Ester