InChI=1S/C16H20N2O4/c1-8-6-10-12(11(8)7-18(22)14(17)20)9(2)16(4-5-16)15(3,21)13(10)19/h6,21-22H,4-5,7H2,1-3H3,(H2,17,20)/t15-/m1/s1