1 H NMR ( 400 MHz , DMSO ) δ 8 . 33 ( d , J = 2 . 9 Hz , 1 H ) , 8 . 06 ( d , J = 3 . 1 Hz , 1 H ) , 7 . 91 ( d , J = 2 . 9 Hz , 1 H ) , 7 . 90 - 7 . 85 ( m , 1 H ) , 7 . 62 - 7 . 53 ( m , 2 H ) , 7 . 50 ( d , J = 2 . 9 Hz , 1 H ) , 7 . 31 ( d , J = 15 . 0 Hz , 1 H ) , 6 . 89 ( s , 2 H ) , 4 . 80 ( s , 2 H ) , 3 . 54 ( s , 2 H ) , 3 . 28 ( s , 3 H ) , 2 . 52 - 2 . 45 ( m , 4 H ) , 2 . 39 - 2 . 30 ( m , 4 H ) , 2 . 14 ( s , 3 H ) . LR - MS ( ESI ) m / z 572 ( M + 1 ) .