1 H NMR ( 400 MHz , DMSO - d 6 ) : δ 7 . 23 ( d , J = 7 . 8 Hz , 1 H ) , 6 . 97 ( d , J = 8 . 1 Hz , 1 H ) , 4 . 33 ( q , J = 6 . 9 Hz , 2 H ) , 4 . 23 - 4 . 19 ( m , 1 H ) , 3 . 76 ( s , 3 H ) , 3 . 38 - 3 . 36 ( m , 2 H ) , 3 . 02 ( s , 3 H ) , 2 . 21 ( br s , 2 H ) , 1 . 31 ( t , J = 6 . 9 Hz , 3 H ) .