1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 67 - 1 . 81 ( m , 4 H ) , 1 . 96 - 2 . 05 ( m , 4 H ) , 2 . 17 ( m , 3 H ) , 2 . 38 ( t , 2 H ) , 2 . 46 ( m , 1 H ) , 2 . 62 ( s , 3 H ) , 2 . 65 ( s , 3 H ) , 2 . 96 ( br - d , 2 H ) , 4 . 30 ( t , 2 H ) , 6 . 52 ( m , 1 H ) , 6 . 95 ( m , 1 H ) , 6 . 98 ( d , 1 H , J = 8 . 1 Hz ) , 7 . 21 - 7 . 38 ( m , 3 H ) , 7 . 76 ( d , 1 H , J = 8 . 1 Hz ) ; MS ( m / e , M +): 405