1 H NMR ( DMSO d 6 ) δ 8 . 69 ( 1 H , br ) , 8 . 61 ( 1 H , d , J = 4 . 6 Hz ) , 7 . 56 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 55 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 48 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 38 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 5 . 54 ( 1 H , t , J = 5 . 3 Hz ) , 5 . 43 ( 1 H , d , J = 4 . 0 Hz ) , 4 . 70 ( 2 H , d , J = 5 . 3 Hz ) , 4 . 63 ( 1 H , d , J = 4 . 0 Hz ) , 4 . 50 ( 2 H , m ) , 2 . 76 - 2 . 55 ( 1 H , m ) , 2 . 14 - 1 . 90 ( 3 H , m ) .