(2-exo,3-exo,5-endo)-7-Oxabicyclo(2.2.1)heptane-2,3,5-tricarboxylic acid 109282-33-9 7-Oxabicyclo(2.2.1)heptane-2,3,5-tricarboxylic acid, (2-exo,3-exo,5-endo)-