1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 3 . 88 ( 2 H , q ) , 4 . 32 - 4 . 36 ( 2 H , m ) , 4 . 61 - 4 . 65 ( 1 H , m ) , 5 . 82 - 5 . 83 ( 1 H , m ) , 7 . 04 ( 1 H , d ) , 8 . 22 ( 1 H , d ) ; m / z = 260 [ M + H ] +.