1 H NMR ( 700 . 03 MHz , DMSO - d 6 ) δ 2 . 45 - 2 . 49 ( 4 H , m ) , 3 . 64 ( 4 H , t ) , 4 . 57 ( 1 H , s ) , 7 . 24 - 7 . 26 ( 1 H , m ) , 7 . 35 ( 2 H , t ) , 7 . 47 - 7 . 48 ( 2 H , m ) , 7 . 54 ( 1 H , d ) , 7 . 69 - 7 . 73 ( 4 H , m ) , 8 . 26 ( 1 H , d ) ; m / z = 507 [ M + H ] +.