1 H NMR ( 300 MHz , DMSO - d 6 ) δ 9 . 06 ( s , 1 H ) , 8 . 91 ( s , 1 H ) , 7 . 91 ( d , 2 H , J = 8 . 7 Hz ) , 7 . 62 ( d , 2 H , J = 8 . 7 Hz ) , 7 . 50 ( d , 2 H , J = 8 . 7 Hz ) , 7 . 33 ( d , 2 H , J = 8 . 9 Hz ) , 2 . 97 ( t , 2 H , J = 7 . 2 Hz ) , 1 . 78 ( m , 5 H ) , 1 . 50 ( m , 4 H ) , 1 . 12 ( m , 2 H ) ; MS ( m / z ) : 410 ( M +).