1 H NMR ( 400 MHz , DMSO - d 6 ) δ = 10 . 65 ( s , 1 H ) , 9 . 04 ( t , J = 6 Hz , 1 H ) , 7 . 72 ( d , J = 4 Hz , 1 H ) , 7 . 69 ( d , J = 8 . 8 Hz , 2 H ) , 7 . 53 ( d , J = 9 Hz , 2 H ) , 7 . 20 ( d , J = 4 Hz , 1 H ) , 4 . 91 - 4 . 83 ( m , 1 H ) , 4 . 29 ( t , J = 10 . 6 Hz , 2 H ) , 4 . 21 ( t , J = 9 Hz , 1 H ) , 3 . 96 ( t , J = 10 . 6 Hz , 2 H ) , 3 . 89 ( dd , J = 9 , 6 Hz , 1 H ) , 2 . 36 ( d , J = 8 Hz , 2 H ) , 1 . 85 - 1 . 75 ( m , 1 H ) , 0 . 82 ( d , J = 6 . 8 Hz , 6 H )