methyl (2R,2'S,3a'S,5''R,6'S,7a'R)-5''-methyl-4''-oxodecahydrodispiro[oxirane-2,3'-benzofuran-2',2''-pyran]-6'-carboxylate

(2S,3R,3aS,5'S,6S,7aR)-3-(hydroxymethyl)-5'-methyl-4'-methylene-6-vinyldecahydro-3H-spiro[benzofuran-2,2'-pyran]-3-ol