1 H NMR ( 300 MHz , DMSO - d 6 ) δ 3 . 44 - 3 . 56 ( 2 H , m ) , 4 . 54 - 4 . 73 ( 2 H , m ) , 7 . 22 ( 1 H , dd , J = 5 . 7 , 2 . 3 Hz ) , 7 . 29 - 7 . 41 ( 2 H , m ) , 7 . 50 ( 1 H , d , J = 2 . 3 Hz ) , 7 . 67 - 7 . 76 ( 2 H , m ) , 7 . 80 ( 1 H , d , J = 2 . 3 Hz ) , 8 . 13 ( 1 H , d , J = 2 . 3 Hz ) , 8 . 67 ( 1 H , d , J = 5 . 7 Hz ) .