Also, where is back 1 oxygen sensor?

 

A bad cat will not cause a misfire. The extra unburnt fuel due to the misfire is what overheats/melts/clogs the cat.

As far as "back 1 oxygen sensor" It sounds like you're taking a reading from an OBD scan tool, which would usually say something like "bank 1 sensor 1" "bank 1 sensor 2" etc. What year Prelude do you have? Also is it saying the o2 sensor is bad, or the Heating circuit? I see the heating circuit go bad much more often.

BTW, it's also possible that the o2 sensor is fine and that it's receiving a faulty reading due to the cat being clogged which could make the CEL come on, so if I were you I'd fix the cat then reset the ecu and see if the o2 sensor CEL comes back. And get that misfire figured out too so you don't go through another cat.

 

How do you know the cat is bad. More often than not you have a faulty O2 and it is incorrectly saying the cat is bad.