1 H NMR ( CDCl 3 ) δ 8 . 55 ( 1 H , dd , J = 4 . 9 , 1 . 8 Hz ) , 7 . 43 ( 1 H , dd , J = 7 . 9 , 1 . 8 Hz ) , 7 . 36 ( 1 H , d , J = 2 . 4 Hz ) , 7 . 30 - 7 . 26 ( 1 H , m ) , 7 . 21 ( 1 H , dd , J = 7 . 9 , 4 . 9 Hz ) , 7 . 17 ( 1 H , dd , J = 8 . 0 , 4 . 9 Hz ) , 6 . 33 ( 1 H , d , J = 1 . 8 Hz ) , 5 . 77 ( 1 H , br ) , 5 . 21 ( 1 H , d , J = 1 . 8 Hz ) , 4 . 47 ( 1 H , dd , J = 15 . 3 , 6 . 1 Hz ) , 4 . 41 ( 1 H , dd , J = 15 . 3 , 6 . 1 Hz ) , 3 . 75 ( 1 H , t , J = 4 . 9 Hz ) , 3 . 75 ( 2 H , br t , J = 4 . 9 Hz ) , 2 . 34 ( 1 H , m ) , 2 . 05 ( 1 H , m ) .