1 H NMR ( DMSO d 6 ) δ 8 . 53 ( 1 H , br ) , 8 . 44 ( 1 H , d , J = 4 . 6 Hz ) , 7 . 52 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 50 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 36 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 23 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 5 . 48 ( 1 H , d , J = 6 . 6 Hz ) , 4 . 90 ( 1 H , m ) , 4 . 44 ( 1 H , d , J = 4 . 6 Hz ) , 4 . 42 ( 1 H , d , J = 4 . 6 Hz ) , 3 . 82 ( 1 H , m ) , 2 . 54 ( 1 H , m ) , 2 . 39 ( 3 H , s ) , 2 . 02 ( 1 H , m ) .