1H-4,9a-Ethanocyclohepta(c)pyran-7-carboxylic acid, 3-((1E,3E)-4-carboxy-1,3-pentadienyl)-3,4,4a,5,6,9-hexahydro-4a-hydroxy-3-methyl-1-oxo-,7-methyl ester, (3R,4R,4aS,9aR)-rel- 82601-41-0