1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 15 ( 6 H , s ) , 1 . 96 ( 2 H , t , J = 6 . 2 Hz ) , 3 . 00 ( 2 H , t , J = 6 . 2 Hz ) , 3 . 40 - 3 . 52 ( 2 H , m ) , 4 . 58 - 4 . 71 ( 2 H , m ) , 6 . 71 ( 1 H , t , J = 7 . 0 Hz ) , 7 . 38 ( 1 H , d , J = 8 . 3 Hz ) , 7 . 60 - 7 . 71 ( 2 H , m ) , 7 . 79 ( 1 H , dd , J = 6 . 6 , 1 . 7 Hz ) , 7 . 95 ( 1 H , d , J = 1 . 9 Hz ) .