2H-Pyran-2,4(3H)-dione, 3,3'-methylenebis(dihydro-6-methyl- 3,3'-Methylenebis(dihydro-6-methyl-2H-pyran-2,4(3H)-dione) 4-19-00-02231 (Beilstein Handbook Reference) 5,5'-Methylenebis(4,6-dioxo-2-methyldihydropyran) 63869-94-3 BRN 0289265