1 H NMR ( CDCl 3 ) δ 8 . 46 ( 1 H , dd , J = 4 . 8 , 1 . 2 Hz ) , 7 . 39 ( 1 H , dd , J = 7 . 9 , 1 . 2 Hz ) , 7 . 13 ( 1 H , dd , J = 7 . 9 , 4 . 8 Hz ) , 6 . 99 ( 1 H , m ) , 6 . 89 ( 1 H , m ) , 6 . 27 ( 1 H , d , J = 1 . 8 Hz ) , 6 . 13 ( 1 H , br t , J = 5 . 5 Hz ) , 5 . 18 ( 1 H , d , J = 1 . 8 Hz ) , 4 . 41 ( 2 H , br d , J = 6 . 1 Hz ) , 3 . 73 ( 1 H , br t , J = 5 . 5 Hz ) , 2 . 65 - 2 . 61 ( 2 H , m ) , 2 . 26 ( 1 H , m ) , 2 . 03 ( 1 H , m ) .