1 H NMR ( 400 MHz , DMSO - d 6 ) δ 9 . 76 ( s , 1 H ) , 8 . 04 ( d , J = 2 . 2 Hz , 1 H ) , 7 . 72 ( d , J = 1 . 7 Hz , 1 H ) , 7 . 62 ( dd , J = 8 . 5 , 0 . 9 Hz , 1 H ) , 7 . 37 ( dd , J = 8 . 5 , 1 . 7 Hz , 1 H ) , 7 . 01 ( dt , J = 1 . 9 , 0 . 9 Hz , 1 H ) , 5 . 45 ( d , J = 9 . 9 Hz , 1 H ) , 3 . 53 ( dt , J = 9 . 9 , 6 . 6 Hz , 1 H ) , 1 . 70 - 1 . 52 ( m , 4 H ) , 1 . 49 - 1 . 29 ( m , 4 H ) .