1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 59 - 1 . 75 ( m , 4 H ) , 1 . 85 - 1 . 90 ( m , 4 H ) , 2 . 16 ( s , 3 H ) , 2 . 23 ( t , 2 H ) , 2 . 38 ( m , 1 H ) , 2 . 78 ( brd , 2 H ) , 4 . 17 ( t , 2 H ) , 6 . 93 ( d , 1 H , J = 7 . 5 Hz ) , 7 . 24 - 7 . 56 ( m , 11 H ) , 7 . 83 ( m , 1 H ) ; MS ( m / e , M +): 486 , 451 , 375 , 346 , 269 , 257