Although I haven't tried that before, I'm not sure if I would. I'd be concerned about yhe syrup just gelling up and not dissolving in your final product. If you wanted to add some caramel notes, why not make some caramel on the stove and try using that? Making caramel sauce is really easy. Just take however much sugar you want to use, add a bit of water (depends on how much sugar you use, but usually 1/2 cup water to 2 cups of sugar works good for me), and cook over medium heat stirring constantly until it looks like caramel.
I've never added that to beer, but I don't see why it wouldn't work. Maybe someone will chime in on this.
Here is a post where someone did exactly what you're looking for http://www.homebrewtalk.com/f79/gold...-apple-149155/