1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 2 . 54 - 2 . 57 ( 4 H , m ) , 3 . 60 - 3 . 63 ( 4 H , m ) , 3 . 70 ( 2 H , s ) , 7 . 27 - 7 . 31 ( 1 H , m ) , 7 . 36 ( 1 H , t ) , 7 . 36 - 7 . 41 ( 1 H , m ) , 7 . 51 - 7 . 53 ( 1 H , m ) , 7 . 53 ( 1 H , t ) , 7 . 67 - 7 . 71 ( 1 H , m ) , 8 . 19 ( 1 H , d ) ; m / z = 413 [ M + H ] +.