InChI=1/C16H14O3S/c1-9-8-10(2)20-16(9)12-7-5-4-6-11(12)14(17)13(16)15(18)19-3/h4-8,17H,1H2,2-3H methyl 3-hydroxy-5'-methyl-3'-methylene-3'H-spiro[indene-1,2'-thiophene]-2-carboxylate spiro[1H-indene-1,2'(3'H)-thiophene]-2-carboxylic acid, 3-hydroxy-5'-methyl-3'-methylene-, methyl ester