How can I use an argument from xargs to evaluate another expression?

I would like to evaluate a basename expression given an argument from xargs. I tested:

find . -name '*.txt' | xargs -I f cp f DIR_OUT/copied_$(basename f)

which gives no file or directory because $(basename f) was not evaluated correctly. I may split it two steps: copying and changing the filename, but I would like to learn how to evaluate an expression with an argument from xargs.