1 H - NMR ( 300 MHz , CDCl 3 ) δ 1 . 76 - 1 . 86 ( m , 6 H ) , 2 . 13 ( m , 2 H ) , 2 . 17 ( s , 3 H ) , 2 . 55 ( m , 1 H ) , 2 . 71 ( t , 2 H ) , 3 . 25 ( brd , 2 H ) , 3 . 84 ( t , 2 H ) , 6 . 95 ( d , 1 H ) , 7 . 19 - 7 . 31 ( m , 3 H ) , 7 . 43 ( s , 1 H , NH ) ; MS ( m / e , M +): 276