1 H NMR ( CDCl 3 ) δ 8 . 49 ( 1 H , m ) , 7 . 52 ( 1 H , dd , J = 8 . 5 , 2 . 4 Hz ) , 4 . 78 ( 1 H , m ) , 3 . 83 ( 3 H , s ) , 3 . 69 ( 1 H , s ) , 2 . 54 ( 1 H , m ) , 2 . 41 ( 1 H , m ) , 2 . 26 - 2 . 11 ( 2 H , m ) .