1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 57 ( m , 2 H ) , 1 . 75 ( m , 2 H ) , 1 . 88 - 1 . 95 ( m , 4 H ) , 2 . 19 ( s , 3 H ) , 2 . 21 ( t , 2 H ) , 2 . 41 ( m , 1 H ) , 2 . 78 ( brd , 2 H ) , 4 . 43 ( t , 2 H ) , 6 . 94 ( d , 1 H , J = 7 . 2 Hz ) , 7 . 24 ( m , 1 H ) , 7 . 29 ( m , 1 H ) , 7 . 40 ( s , 1 H ) , 7 . 56 ( m , 4 H ) , 7 . 72 ( d , 2 H , J = 8 . 4 Hz ) , 8 . 14 ( s , 1 H ) ; MS ( m / e , M +): 512