1 H NMR ( 400 MHz , DMSO - d 6 ) δ = 8 . 94 ( t , J = 5 . 2 Hz , 1 H ) , 7 . 65 ( d , J = 4 . 0 Hz , 1 H ) , 7 . 62 ( d , J = 8 . 0 Hz , 2 H ) , 7 . 53 ( d , J = 8 . 0 Hz , 2 H ) , 7 . 15 ( d , J = 4 . 0 Hz , 1 H ) , 4 . 83 - 4 . 78 ( m , 1 H ) , 4 . 16 ( dd , J = 8 . 8 , 8 . 8 Hz , 1 H ) , 3 . 89 ( dd , J = 8 . 8 , 5 . 2 Hz , 4 H ) , 3 . 58 - 3 . 55 ( m , 2 H ) , 3 . 02 ( s , 3 H )