1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 68 - 1 . 83 ( m , 4 H ) , 1 . 94 - 2 . 10 ( m , 4 H ) , 2 . 17 ( s , 3 H ) , 2 . 36 ( br t , 2 H , J = 6 . 8 Hz ) , 2 . 47 ( m , 1 H ) , 2 . 64 ( s , 3 H ) , 2 . 93 ( m , 2 H ) , 4 . 50 ( br t , 2 H , J = 7 . 1 Hz ) , 6 . 97 ( m , 1 H ) , 7 . 21 - 7 . 34 ( m , 4 H ) , 7 . 42 ( m , 2 H ) , 7 . 49 ( m , 1 H ) , 7 . 82 ( m , 1 H ) , 7 . 99 ( s , 1 H ) ; MS ( m / e , M +): 457 ( M +), 257 , 231 , 120 .