1 H NMR ( 300 MHz , DMSO - d 6 ) δ 3 . 16 ( 2 H , t , J = 8 . 5 Hz ) , 3 . 40 - 3 . 50 ( 2 H , m , J = 6 . 4 Hz ) , 4 . 51 - 4 . 71 ( 4 H , m ) , 6 . 47 - 6 . 55 ( 2 H , m ) , 6 . 70 ( 1 H , t , J = 7 . 2 Hz ) , 6 . 99 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 22 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 51 ( 2 H , d , J = 8 . 3 Hz ) , 7 . 62 ( 1 H , d , J = 6 . 8 Hz ) , 7 . 76 ( 1 H , d , J = 5 . 3 Hz ) .