1 H NMR ( 400 MHz , DMSO - d 6 ) δ 9 . 80 ( s , 1 H ) , 8 . 29 ( dd , J = 12 . 0 , 2 . 0 Hz , 1 H ) , 7 . 54 ( dd , J = 6 . 4 , 2 . 0 Hz , 1 H ) , 7 . 28 ( d , J = 8 . 0 Hz , 1 H ) , 7 . 04 ( d , J = 8 . 0 Hz , 1 H ) , 5 . 81 ( dd , J = 10 . 4 , 3 . 2 Hz , 1 H ) , 4 . 16 - 4 . 32 ( m , 4 H ) , 3 . 76 ( s , 3 H ) , 3 . 10 ( s , 3 H ) , 2 . 21 ( s , 3 H ) , 1 . 19 ( t , J = 7 . 2 Hz , 3 H ) . LC - MS : 480 . 2 ( [ M + 1 ] +).