1 H NMR ( 400 MHz , CDCl 3 ) δ 8 . 77 ( s , 1 H ) , 8 . 34 ( s , 1 H ) , 8 . 06 ( s , 1 H ) , 7 . 97 ( s , 1 H ) , 7 . 80 - 7 . 51 ( m , 3 H ) , 7 . 37 ( s , 2 H ) , 6 . 54 ( s , 1 H ) , 3 . 54 ( s , 2 H ) , 2 . 48 ( s , 4 H ) , 2 . 34 ( s , 4 H ) , 2 . 22 ( s , 3 H ) , 2 . 14 ( s , 3 H ) , 2 . 00 ( s , 2 H ) . LR - MS ( ESI ) m / z 508 ( M + 1 ) .