1 H NMR ( CDCl 3 ) δ 8 . 53 ( 1 H , dd , J = 4 . 9 , 1 . 2 Hz ) , 7 . 99 ( 1 H , br t , J = 5 . 5 Hz ) , 7 . 70 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 39 ( 1 H , dd , J = 7 . 9 , 4 . 9 Hz ) , 7 . 06 ( 1 H , m ) , 6 . 89 ( 1 H , m ) , 4 . 45 ( 2 H , m ) , 4 . 04 ( 1 H , br t , J = 5 . 5 Hz ) , 3 . 03 ( 1 H , ddd , J = 17 . 7 , 10 . 4 , 4 . 9 Hz ) , 2 . 65 ( 1 H , m ) , 2 . 50 - 2 . 34 ( 2 H , m ) .