InChI=1S/C21H20O7/c1-20(2)7-6-12-15(28-20)5-4-13(18(12)26-3)21(25)10-27-16-9-11(22)8-14(23)17(16)19(21)24/h4-9,22-23,25H,10H2,1-3H3