1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 61 - 1 . 75 ( m , 4 H ) , 1 . 88 - 1 . 96 ( m , 4 H ) , 2 . 17 ( s , 3 H ) , 2 . 26 ( t , 2 H ) , 2 . 42 ( m , 1 H ) , 2 . 81 ( brd , 2 H ) , 4 . 35 ( t , 2 H ) , 6 . 96 ( d , 1 H ) , 7 . 25 - 7 . 79 ( m , 11 H ) , ; MS ( m / e , M +): 520 , 492 , 409 , 380 , 302 , 257 , 231