1 H NMR ( 400 MHz , DMSO - d 6 ) δ 9 . 73 ( s , 1 H ) , 8 . 47 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 82 ( t , J = 8 . 0 Hz , 1 H ) , 7 . 60 ( d , J = 7 . 2 Hz , 1 H ) , 7 . 27 ( d , J = 8 . 0 Hz , 1 H ) , 7 . 02 ( d , J = 8 . 0 Hz , 1 H ) , 5 . 81 ( dd , J = 10 . 8 , 3 . 2 Hz , 1 H ) , 4 . 15 - 4 . 35 ( m , 4 H ) , 3 . 76 ( s , 3 H ) , 3 . 10 ( s , 3 H ) , 2 . 18 ( s , 3 H ) , 1 . 17 ( t , J = 7 . 2 Hz , 3 H ) . LC - MS : 462 . 2 ( [ M + 1 ] +).