1 H NMR ( 300 MHz , DMSO ) δ 7 . 45 ( t , J = 7 . 5 Hz , 1 H ) , 7 . 26 ( d , J = 8 . 1 Hz , 1 H ) , 7 . 04 - 6 . 90 ( m , 3 H ) , 6 . 49 ( s , 2 H ) , 5 . 79 - 5 . 71 ( m , 1 H ) , 4 . 25 - 4 . 16 ( m , 4 H ) , 3 . 76 ( s , 3 H ) , 3 . 08 ( s , 3 H ) , 1 . 20 ( t , J = 6 . 9 Hz , 3 H ) .