13161-75-6 17944-23-9 2-Butenoic acid, 2-methyl-, 9-(acetyloxy)-9,10-dihydro-8,8-dimethyl-2-oxo-2H,8H-benzo(1,2-b:3,4-b')dipyran-10-yl ester, (9R-(9alpha,10alpha(Z)))- Pteryxin