1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 67 ( m , 4 H ) , 1 . 96 ( m , 4 H ) , 2 . 15 ( s , 3 H ) , 2 . 29 ( t , 2 H ) , 2 . 43 ( s , 3 H ) 2 . 84 ( brd , 2 H ) , 4 . 36 ( t , 2 H ) , 6 . 94 ( d , 1 H , J = 7 . 5 Hz ) , 7 . 24 ( m , 2 H ) , 7 . 29 - 7 . 51 ( m , 7 H ) 7 . 58 ( s , 1 H ) , 7 . 80 ( d , 1 H , J = 4 . 2 Hz ) ; MS ( m / e , M +): 505