1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 25 ( d , 6 H ) , 1 . 52 - 1 . 86 ( m , 4 H ) , 2 . 12 ( m , 2 H ) , 2 . 46 ( m , 1 H ) , 2 . 52 ( m , 1 H ) , 2 . 79 ( t , 2 H ) , 2 . 86 ( brd , 2 H ) , 4 . 38 ( t , 2 H ) , 6 . 92 ( d , 1 H , J = 7 . 2 Hz ) , 7 . 10 ( s , 1 H ) , 7 . 22 - 7 . 35 ( m , 3 H ) , 7 . 47 ( m , 2 H ) , 7 . 52 ( d , 2 H , J = 8 . 4 Hz ) , 7 . 79 ( d , 2 H , J = 8 . 4 Hz ) , 7 . 84 ( m , 1 H ) ; MS ( m / e , M +): 500