1 H NMR ( 400 MHz , DMSO ) δ 10 . 83 ( s , 1 H ) , 8 . 17 ( d , J = 1 . 9 Hz , 1 H ) , 8 . 05 ( dd , J = 6 . 8 , 2 . 2 Hz , 1 H ) , 8 . 02 - 7 . 92 ( m , 2 H ) , 7 . 86 ( ddd , J = 8 . 6 , 4 . 9 , 2 . 2 Hz , 1 H ) , 7 . 73 ( d , J = 8 . 5 Hz , 1 H ) , 7 . 61 ( dd , J = 7 . 5 , 1 . 9 Hz , 1 H ) , 7 . 45 ( dd , J = 9 . 8 , 8 . 7 Hz , 1 H ) , 6 . 58 ( dd , J = 7 . 5 , 4 . 9 Hz , 1 H ) , 6 . 44 ( s , 2 H ) , 3 . 61 ( s , 2 H ) , 2 . 60 ( s , 4 H ) , 2 . 51 - 2 . 39 ( m , 4 H ) , 2 . 35 ( s , 3 H ) . LR - MS ( ESI ) m / z 512 ( M + 1 ) .