1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 67 - 1 . 83 ( m , 4 H ) , 1 . 96 - 2 . 06 ( m , 4 H ) , 2 . 17 ( m , 3 H ) , 2 . 36 ( t , 2 H ) , 2 . 46 ( m , 1 H ) , 2 . 65 ( s , 3 H ) , 2 . 72 ( s , 3 H ) , 2 . 94 ( br - d , 2 H ) , 4 . 27 ( t , 2 H ) , 6 . 95 ( d , 1 H , J = 6 . 8 Hz ) , 7 . 21 - 7 . 42 ( m , 4 H ) , 8 . 02 ( s , 1 H ) ; MS ( m / e , M +): 484 , 469 , 267 , 245 , 231