Minato can get to the place Kakashi is if Kakash still has the Kunai knife that Minato gave him as a present when he became a jonin. In the anime every once in a while you see Kakashi with it so I believe he still has it. Minato does not have to worry about dying at the moment so he has nothing to lose by trying to reach Kakashi after he sees Naruto that is.
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