1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 3 . 12 ( 4 H , m ) , 3 . 75 ( 4 H , m ) , 6 . 69 ( 2 H , d ) , 6 . 87 ( 2 H , d ) , 7 . 67 ( 1 H , d ) , 8 . 28 ( 1 H , d ) , 8 . 87 ( 1 H , s ) ; m / z = 365 [ M + H ] +.