InChI=1S/C22H20O5S/c1-2-21(16-7-4-3-5-8-16)22(17-11-13-19(23)14-12-17)18-9-6-10-20(15-18)27-28(24,25)26/h3-15,23H,2H2,1H3,(H,24,25,26)/b22-21+