1 H NMR ( DMSO d 6 ) δ 8 . 74 ( 1 H , m ) , 8 . 60 ( 1 H , br s ) , 7 . 58 ( 0 . 4 H , d , J = 7 . 9 Hz ) , 7 . 55 ( 0 . 6 H , d , J = 7 . 9 Hz ) , 7 . 46 ( 1 H , br s ) , 7 . 38 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 7 . 35 ( 1 H , br s ) , 5 . 41 ( 1 H , br s ) , 4 . 61 ( 1 H , m ) , 4 . 48 ( 0 . 8 H , d , J = 4 . 6 Hz ) , 4 . 43 ( 1 . 2 H , d , J = 4 . 6 Hz ) , 2 . 80 - 1 . 75 ( 4 H , m ) , 2 . 42 ( 1 . 2 H , s ) , 2 . 38 ( 1 . 8 H , s ) .