1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 1 . 46 ( 2 H , m ) , 1 . 65 ( 2 H , m ) , 2 . 45 ( 1 H , m ) , 2 . 58 ( 2 H , m ) , 3 . 02 ( 2 H , m ) , 6 . 68 ( 2 H , d ) , 7 . 00 ( 2 H , d ) , 9 . 15 ( 1 H , s ) ; m / z = 178 [ M + H ] +.