I had this problem and I carefully did the following. But in situations like this you should really seriously consider calling a plumber. It reminds both them and us what they get paid for.
1.5 inches is still quite a good stub? You might be able to carefully cut the pipe before the dimple with a hacksaw blade leaving enough room for another compression stop.
I had about an inch to work with so if this is not possible:
1) Learn how to solder. Stop now if this is your first time and call a plumber. You will only get one shot at this because the stub is so small.
2) Keep a fire extinguisher nearby or bucket of water.
3) outside of the cabinet, solder a coupling on to a piece of pipe to bring the stub out to where you want it.
4) Go under the cabinet and solder the other end of the coupling onto the pipe stub. Careful, careful, careful. Use just enough heat to get the job done. You do not want to burn the house down. It's a risky job.
I also soldered a threaded nipple onto my pipe extension and now use screw-on shut-offs. Apply three wraps of teflon tape and then a layer of pipe dope before screwing on the valve. Solder the nipple on outside the cupboard if you want one of these.
Note: do most of your soldering outside of the cupboard and only go under to make the final connection.
Make sure the short pipe stub does not slide back into the wall at any time during the process.
You should also try to buy a fireproof mat (available at any shop) which you should be able to slip over the pipe to be soldered to protect the wood behind. Cut the mat to make a small hole in it to push the stub through. Again, make sure the short pipe stub does not slide back into the wall.
Don't point the torch at the wooden cabinet wall. Point it at the pipe.
Remember your water will be off when you do this, so you must have lots of water ready before you do the job in case you start a fire.
And now all the real plumbers on here start posting pictures of house fires...