4,10-dioxatricyclo[5.2.1.0(2,6)]decan-8-en-3-one

3a,4,7,7a-tetrahydro-4,7-epoxyisobenzofuran-1(3H)-one

4,7-epoxy-3a,4,7,7a-tetrahydroisobenzofuran-1(3h)-one