1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 65 - 1 . 82 ( m , 4 H ) , 1 . 92 - 2 . 05 ( m , 4 H ) , 2 . 15 ( m , 3 H ) , 2 . 37 ( m , 2 H ) , 2 . 45 ( m , 1 H ) , 2 . 92 ( br - d , 2 H ) , 4 . 16 ( t , 2 H ) , 6 . 91 ( d , 1 H , J = 6 . 7 Hz ) , 7 . 20 - 7 . 53 ( m , 10 H ) , 7 . 83 ( d , 1 H , J = 7 . 3 Hz ) , 7 . 98 ( d , 1 H ) ; MS ( m / e , M +): 578 , 451 , 347 , 256 , 231