1 H NMR ( CDCl 3 ) δ 8 . 61 ( 1 H , br d , J = 4 . 6 Hz ) , 7 . 71 ( 1 H , d , J = 7 . 3 Hz ) , 7 . 65 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 49 ( 1 H , ddd , J = 7 . 9 , 2 . 0 , 1 . 3 Hz ) , 7 . 41 ( 1 H , dd , J = 7 . 9 , 7 . 3 Hz ) , 7 . 32 ( 1 H , br ) , 7 . 24 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 4 . 79 - 4 . 71 ( 3 H , m ) , 4 . 35 ( 1 H , s ) , 2 . 57 ( 1 H , m ) , 2 . 44 - 2 . 27 ( 2 H , m ) , 2 . 03 ( 1 H , m ) .