1 H NMR ( CDCl 3 ) δ 8 . 54 ( 1 H , br dd , J = 4 . 9 , 1 . 8 Hz ) , 7 . 42 ( 1 H , d , J = 1 . 8 Hz ) , 7 . 36 ( 1 H , br dd , J = 7 . 9 , 1 . 8 Hz ) , 7 . 28 - 7 . 20 ( 3 H , m ) , 6 . 86 ( 1 H , br d , J = 5 . 5 Hz ) , 5 . 00 ( 1 H , br ) , 3 . 98 ( 1 H , d , J = 11 . 0 Hz ) , 3 . 77 - 3 . 62 ( 2 H , m ) , 3 . 68 ( 1 H , d , J = 11 . 0 Hz ) , 3 . 48 ( 1 H , s ) , 3 . 07 - 3 . 03 ( 2 H , m ) , 2 . 83 ( 1 H , m ) , 2 . 18 - 1 . 98 ( 3 H , m ) .