[PLUG] RJ45 to Coax adapter?

[Sasha Romanosky]

I have recently moved into a new apartment and need to have ethernet run
to a separate room that shares a wall with the room that has it. 

The previous tenant drilled a hole and fed a coax cable through the
wall. If I could find an RJ45-to-Coax (type "F"?) adapter I could just
use this.

I could go wireless or drill another hole, but I'd rather not. I checked
with fry's and found all kinds of adapters and converters but not this.
Does anyone know if such an adapter exists?

Cheers,
sasha