1 H NMR ( 300 MHz , DMSO - d 6 ) δ 3 . 41 - 3 . 51 ( 2 H , m ) , 4 . 59 - 4 . 72 ( 2 H , m ) , 6 . 71 ( 1 H , t , J = 7 . 0 Hz ) , 7 . 03 - 7 . 12 ( 2 H , m ) , 7 . 17 ( 1 H , d , J = 8 . 3 Hz ) , 7 . 31 - 7 . 43 ( 1 H , m ) , 7 . 54 - 7 . 60 ( 2 H , m ) , 7 . 62 - 7 . 72 ( 2 H , m ) , 7 . 75 - 7 . 86 ( 2 H , m ) .