1 H NMR ( 400 MHz , DMSO - d 6 ) δ 9 . 77 ( s , 1 H ) , 8 . 69 ( d , J = 1 . 2 Hz , 1 H ) , 7 . 81 ( d , J = 1 . 2 Hz , 1 H ) , 7 . 27 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 03 ( d , J = 8 . 0 Hz , 1 H ) , 5 . 79 ( m , 1 H ) , 4 . 31 - 4 . 30 ( m , 1 H ) , 4 . 20 - 4 . 16 ( m , 3 H ) , 3 . 76 ( s , 3 H ) , 3 . 09 ( s , 3 H ) , 2 . 20 ( s , 3 H ) , 1 . 19 ( t , J = 7 . 2 Hz , 3 H ) .