A similar problem was already covered in the question Can't backup iPhone6 without entering PIN As far as I'm aware, entering the pass code is a security feature when you backup for the first time to a different iTunes/computer. You can't get around it, however its possible that Apple will be...

I have recently broken the screen on my iPhone 6 and want to back everything up before I take it into apple to be repaired. My problem is when I go to back the phone up in iTunes, it wants my pincode. I can't put my pincode in as my screen is broken! The screen seems to be responding to key pr...