Change to 11x32 Cassette with new derailleur

I currently have a 11x25 rear cassette and 52/36 crankset with ultegra 6700 components. I want to change to a 11x32 cassette. I don't know if I need to change my rear derailleur and if I do I was thinking about the Ultegra 6800 or a Dura Ace derailleur. Do I also need to get a new chain? I did the...