1 H NMR ( 400 MHz , CDCl 3 ) δ 9 . 07 ( s , 1 H ) , 8 . 33 ( s , 1 H ) , 8 . 04 ( d , J = 12 . 5 Hz , 2 H ) , 7 . 89 ( d , J = 12 . 0 Hz , 2 H ) , 7 . 55 ( d , J = 8 . 0 Hz , 2 H ) , 7 . 37 ( s , 1 H ) , 3 . 54 ( s , 2 H ) , 2 . 64 ( s , 2 H ) , 2 . 48 ( s , 4 H ) , 2 . 34 ( s , 4 H ) , 2 . 13 ( s , 3 H ) . LR - MS ( ESI ) m / z 562 ( M + 1 ) .