InChI=1S/C21H20N2O4S/c1-13(2)19-20(24)17(21(25)23(19)12-14-8-4-3-5-9-14)18-15-10-6-7-11-16(15)28(26,27)22-18/h3-11,13,19,24H,12H2,1-2H3/t19-/m0/s1