1 H NMR ( DMSO d 6 ) δ 8 . 73 ( 1 H , br ) , 8 . 45 ( 1 H , d , J = 4 . 6 Hz ) , 7 . 79 ( 1 H , dd , J = 7 . 9 , 1 . 3 Hz ) , 7 . 66 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 57 ( 1 H , dd , J = 7 . 9 , 7 . 3 Hz ) , 7 . 49 ( 1 H , d , J = 7 . 3 Hz ) , 7 . 24 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 5 . 14 ( 1 H , d , J = 4 . 0 Hz ) , 4 . 56 ( 1 H , br ) , 4 . 52 - 4 . 43 ( 2 H , m ) , 3 . 85 ( 1 H , dd , J = 5 . 9 , 5 . 3 Hz ) , 2 . 25 - 2 . 18 ( 2 H , m ) , 1 . 92 ( 1 H , m ) , 1 . 69 ( 1 H , m ) .