1 H NMR ( CDCl 3 , 300 MHz ) δ 3 . 22 ( t , 4 H , J = 4 . 5 Hz ) , 4 . 13 ( t , 4 H , J = 4 . 2 Hz ) , 6 . 70 ( s , 1 H ) , 7 . 02 ― 7 . 11 ( m , 5 H ) , 7 . 23 ( s , 1 H ) , 8 . 21 ( s , 1 H ) , 10 . 67 ( brs , 1 H , NH ) .