KJV 1 Peter 4:1-6, but especially verse 6, might have a bit of an answer about this idea in the decades after Christ left the earth.
6 For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but
live according to God in the spirit.
To me that means that the basic doctrinal text of Christianity doesn't entirely preclude the notion. The prime example of teaching this doctrine would actually be Peter.
Whether or not pre-500 orthodox clergymen actually taught it as Peter said it is obviously going to be less common. I don't know any specifics.
I would count being able to come to Christ and learn of Him postmortem to be about as good as baptism as you can get when you're dead, since most Christians' definition of the afterlife and what we can do in it are really fuzzy.
However, the only specific denomination of Christianity I know of that practices any sort of proxy ordinance for the dead (baptism being the first) is the Church of Jesus Christ of Latter Day Saints.
Cit: I'm a member.