I'm not sure what you mean by exception cast. The easiest way to get an exception from the business layer to the UI is just to throw it (or not catch it) - it will bubble up until you handle it, and if you only handle it in the UI that's where it will end up.
One thing that's quite common (and that
might be what you're looking for) is when you want the business layer to throw a particular special type of exception so the UI doesn't have to know about the internal workings. Then you can catch a general exception, wrap it in your special one, and throw that. The
pattern looks something like this: