Dropbox PostUrl Save_Url

Good day Im trying to figure out a PostUrl to save a url file into a dropbox account, but I got a 400 sintax error, I try to do the same curl dropbox example with a postUrl, I try always encoding the url param. What I should doing wrong?

curl https://api.dropbox.com/1/save_url/auto/images/downloaded.png \

-d url="https://dl.dropboxusercontent.com/s/deroi5nwm6u7gdf/advice.png" \

-H "Authorization: Bearer <ACCESS TOKEN>"

headerMap = {"Authorization": "Bearer <MY TOKEN>", "url": "https://dl.dropboxusercontent.com/s/deroi5nwm6u7gdf/advice.png"};
Respuesta = postUrl("https://api.dropbox.com/1/save_url/auto/API/downloaded.png",headerMap,false);
alert Respuesta;