Sync iPhone apps with iTunes without deleting them

I have a few apps on my iPhone, and would like to sync them with iTunes without erasing them from my phone. Is this possible without downloading them all again?

I just tested this out by alt clicking iTunes, creating a new library, and connecting my iPod. This happens when you try to sync with a library that is not the same as the one your iPod is associated with.

* cancel the sync
* secondary click the iPod on the left
* click "transfer purchases"

Afterwards, you can sync, and everything will be erased and rewritten to the iPod.

I'm not sure why Apple makes this so confusing. The only reason I can come up with is that they want people to have to repurchase stuff but that seems a little over the top even from Apple.

From an Apple.SO answer:

I had this same issue after I recreated my iTunes library. This may be totally off because it was about a month ago, but I think I did this:

• canceled the sync
• clicked on the iPod under devices or whatever (maybe I secondary clicked)
• I think after I clicked (or secondary clicked) on it, there was an option to copy purchased items