1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 1 . 68 - 1 . 71 ( 2 H , m ) , 2 . 61 - 2 . 69 ( 2 H , m ) , 3 . 44 - 3 . 51 ( 2 H , m ) , 4 . 20 - 4 . 24 ( 2 H , m ) , 5 . 47 ( 1 H , s ) , 7 . 26 - 7 . 30 ( 1 H , m ) , 7 . 36 - 7 . 40 ( 2 H , m ) , 7 . 69 ( 1 H , d ) , 7 . 84 - 7 . 86 ( 1 H , m ) , 8 . 26 ( 1 H , d ) ; m / z = 398 [ M + H ] +.