Synonyms: 2-Butenoicacid, 2-methyl-,2,3,3a,5,6,9,9a,9b-octahydro-5-hydroxy-6,9-dimethyl-3-methylene-2-oxo-4H-6a,9-ethenofuro[2',3':3,4]cyclohepta[1,2-c][1,2]dioxol-6-ylester, [3aS-[3aa,5a,6a(E),6ab,9b,9aa,9bb]]-; 4H-6a,9-Ethenofuro[2',3':3,4]cyclohepta[1,2-c][1,2]dioxole,2-butenoic acid deriv.; a-Peroxyachifolid; a-Peroxyachifolide