InChI=1S/C14H14O4/c15-13(16)11-9-7-5-3-1-2-4-6-8-10-12-14(17)18/h1-12H,(H,15,16)(H,17,18)/b3-1-,4-2+,7-5+,8-6+,11-9-,12-10-