InChI=1S/C21H20O7/c1-11(9-22)3-5-13-15(23)8-17(25)19-20(26)14(10-28-21(13)19)12-4-6-18(27-2)16(24)7-12/h3-4,6-8,10,22-25H,5,9H2,1-2H3/b11-3+