1 H NMR ( CDCl 3 ) δ 8 . 88 ( 1 H , dd , J = 4 . 6 , 1 . 3 Hz ) , 7 . 74 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 71 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 63 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 51 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 7 . 40 ( 1 H , dd , J = 7 . 9 , 7 . 9 Hz ) , 7 . 33 ( 1 H , br d , J = 5 . 9 Hz ) , 4 . 72 ( 2 H , d , J = 5 . 9 Hz ) , 3 . 17 ( 1 H , m ) , 3 . 01 ( 1 H , m ) , 2 . 59 ( 1 H , m ) .