1 H NMR ( 300 . 132 MHz , DMSO - d 6 ) δ 2 . 60 - 2 . 67 ( 4 H , m ) , 3 . 61 - 3 . 69 ( 4 H , m ) , 3 . 81 ( 2 H , s ) , 7 . 09 - 7 . 21 ( 2 H , m ) , 7 . 43 - 7 . 48 ( 1 H , m ) , 7 . 53 - 7 . 62 ( 2 H , m ) , 8 . 25 ( 1 H , d ) , 12 . 33 ( 1 H , s ) ; m / z = 403 [ M + H ] +.