1 H NMR ( 400 MHz , DMSO ) δ 8 . 33 ( d , J = 3 . 0 Hz , 1 H ) , 8 . 11 - 7 . 78 ( m , 3 H ) , 7 . 70 ( dd , J = 15 . 0 , 3 . 0 Hz , 1 H ) , 7 . 62 - 7 . 43 ( m , 2 H ) , 7 . 31 ( d , J = 15 . 0 Hz , 1 H ) , 6 . 89 ( s , 2 H ) , 6 . 53 ( t , J = 15 . 0 Hz , 1 H ) , 3 . 54 ( s , 2 H ) , 2 . 68 ( dd , J = 15 . 4 , 5 . 2 Hz , 4 H ) , 2 . 33 ( dd , J = 15 . 4 , 5 . 4 Hz , 4 H ) , 1 . 75 ( s , 1 H ) . ( ESI ) m / z 514 ( M + 1 ) .