1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 1 . 67 - 1 . 94 ( 6 H , m ) , 2 . 17 ( 2 H , m ) , 2 . 87 - 2 . 98 ( 4 H , m ) , 3 . 12 ( 2 H , m ) , 3 . 44 ( 4 H , m ) , 3 . 62 ( 2 H , m ) , 4 . 44 ( 2 H , m ) , 7 . 25 - 7 . 35 ( 4 H , m ) , 7 . 68 ( 1 H , d ) , 8 . 26 ( 1 H , d ) ; m / z = 516 [ M + H ] +.