1 H NMR ( CDCl 3 ) δ 8 . 48 ( 1 H , m ) , 7 . 42 ( 1 H , dd , J = 8 . 6 , 1 . 8 Hz ) , 6 . 27 ( 1 H , s ) , 5 . 28 ( 1 H , s ) , 3 . 83 ( 3 H , s ) , 2 . 82 ( 2 H , m ) , 2 . 45 ( 1 H , m ) , 2 . 29 ( 1 H , m ) .