1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 1 . 39 - 1 . 42 ( 2 H , m ) , 2 . 01 ( 2 H , td ) , 2 . 33 ( 3 H , s ) , 2 . 73 - 2 . 76 ( 2 H , m ) , 2 . 88 - 2 . 94 ( 2 H , m ) , 4 . 96 ( 1 H , s ) , 7 . 06 ( 1 H , d ) , 7 . 47 ( 1 H , s ) , 8 . 36 ( 1 H , d ) ; m / z = 193 [ M + H ] +.