ethyl-4-(o-carboxyphenyl)-4-oxo-butanoate

isoshihunine

spiro<(2-oxo-tetrahydrofuran)-5,3'-(1'-oxo-benzofuran)>

spiro[isobenzofuran-1(3H),2'-tetrahydrofuran]-3-one

ethyl 3-[3-oxoisobenzofuran-1(3H)-ylidene]propanoate