1 H NMR ( 400 MHz , DMSO - d 6 ) δ 8 . 92 ( t , J = 6 . 0 Hz , 1 H ) , 7 . 93 ( d , J = 8 . 8 Hz , 1 H ) , 7 . 87 ( d , J = 2 . 0 Hz , 1 H ) , 7 . 62 ( d , J = 4 . 0 Hz , 1 H ) , 7 . 60 ( d , J = 2 . 4 Hz , 1 H ) , 7 . 14 ( d , J = 4 . 0 Hz , 1 H ) , 4 . 86 - 4 . 81 ( m , 1 H ) , 4 . 18 ( t , J = 9 . 2 Hz , 1 H ) , 3 . 84 ( dd , J = 9 . 2 , 6 . 0 Hz , 1 H ) , 3 . 56 ( t , J = 5 . 6 Hz , 2 H )