iPad 2 iOS 9 sync problem with I tunes on older minimac

Having made a bid mistake uploading IOS 9 on my iPad 2, I found many functions didn't work , so following apples online guide I successfully backed up the iPad on my minimac iTunes, version 11.4 , wiped the IPAD to do a reinstall backup, but now after the hard reset my iPad won't connect to iTunes , I get a message stating" you need to update iTunes to connect to this iPad " , trouble is my 2008 minimac will not upgrade beyond iTunes 11.4- so here I am, having followed apples suggestion to fix my issues and now in a really bad mess because I can't access the back up files ! Many very important docs. The back up was to my older minimac PC iTunes . Again following apples advice , I Did the same with my iPhone 5 a couple of weeks ago and that worked fine and connects iOS 9.1 to iTunes 11.4. Can anyone suggest how I can get my iPad to connect and back up - two unsuccessful ( expensive) calls to apple and their tech guys were stuck?

or can I roll the IPAD software back , or somehow get the latest iTunes on my minimac

Please don't tell me I've got to buy a newer minimac, mac air and iPads just to get everything talking together - When until iOS 9 all were working fine ? I moved from MS just to get away from this sort of issue.