1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 05 ( m , 2 H ) , 1 . 51 ( brd , 2 H ) , 1 . 68 - 1 . 82 ( m , 4 H ) , 1 . 97 ( m , 2 H ) , 2 . 23 ( m , 1 H ) , 2 . 25 ( s , 3 H ) , 2 . 51 ( brd , 2 H ) 4 . 05 ( t , 2 H ) , 5 . 98 ( brs , 1 H , NH 2 ) , 6 . 79 ( d , 1 H , J = 7 . 5 Hz ) , 6 . 87 ( s , 1 H ) , 7 . 18 ( dd , 1 H ) , 7 . 35 - 7 . 37 ( m , 3 H ) , 7 . 55 ( dd , 1 H ) , 7 . 48 ( d , 1 H ) , 7 . 83 - 7 . 88 ( m , 2 H ) , 7 . 99 ( s , 1 H ) , 8 . 01 ( d , 1 H , J = 8 . 1 Hz ) , 8 . 78 ( s , 1 H ) ; MS ( m / e , M +): 495