1 H NMR ( CDCl 3 ) δ 8 . 68 ( 1 H , br s ) , 7 . 462 ( 1 H , d , J = 1 . 8 Hz ) , 7 . 456 ( 1 H , d , J = 2 . 4 Hz ) , 7 . 37 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 27 ( 1 H , dd , J = 7 . 9 , 1 . 8 Hz ) , 7 . 23 ( 1 H , br ) , 4 . 64 ( 1 H , dd , J = 15 . 3 , 6 . 1 Hz ) , 4 . 61 ( 1 H , dd , J = 15 . 3 , 6 . 1 Hz ) , 3 . 11 ( 1 H , m ) , 2 . 97 ( 1 H , m ) , 2 . 79 ( 1 H , m ) , 2 . 54 ( 1 H , m ) , 2 . 40 ( 3 H , s ) .