1beta,4beta-Epoxy-5beta-hydroxy-10alphaH-xantha-11(13)-en-12,8beta-olide InChI=1/C15H22O4/c1-8-6-12-11(10(3)14(17)18-12)7-13(16)15(8)5-4-9(2)19-15/h8-9,11-13,16H,3-7H2,1-2H3/t8-,9?,11+,12+,13+,15-/m0/s rel-(3aR,5R,5'S,6S,7S,8aR)-5-hydroxy-5',7-dimethyl-3-methyleneoctahydro-3'H-spiro[cyclohepta[b]furan-6,2'-furan]-2(3H)-one spiro[6H-cyclohepta[b]furan-6,2'(3'H)-furan]-2(3H)-one, octahydro-5-hydroxy-5',7-dimethyl-3-methylene-, (3aR,5R,5'S,6S,7S,8aR)-