1 H NMR ( 399 . 9 MHz , CDCl 3 ) δ 1 . 37 ( 6 H , s ) , 2 . 62 ( 4 H , t ) , 3 . 57 ( 4 H , t ) , 6 . 99 ( 2 H , d ) , 7 . 04 ( 1 H , d ) , 7 . 51 ( 2 H , dd ) , 7 . 90 ( 1 H , d ) ; m / z = 409 [ M + H ] +.