I'm not a pro plumber, but I can't think of an easy way. The venting code may also pose a problem, depending on your local code. An air admittance valve would be easiest, but not all code permit it.

That said, cutting six feet of concrete is pretty easy with the right tools.

Thanks for your comments. I'm out of town so I don't have to comply with city code. I moved the plumbing for a toilet in the same house and made a horrible mess with all of the dust. In the absence of an easy fix, I have another location for the sink that I also like.

Move the sink. The plumbing code isn't there just to annoy you - without proper venting the sink won't drain - period!

We had to dig a trench in our slab to put a prep sink in our island, which was about 10 feet from the existing plumbing, and it really wasn't that big of a deal. It did create an enormous amount of dust, but the room was blocked off fairly well with plastic, so the dust was contained. For our design, it was well worth it.