Itunes ver vs Macbook pro operating ver conflict

I recently upgraded my iPhone to ver 9.1. Now it won't sync with iTunes. A message says i have to download a newer version. I have ver 11.4. The newest version on the iTunes site is 12.3.1. my Mac Pro is running 10.6.8. To download iTunes, it says I have to have a newer operating system. Am I going to have to download El Capitan in order to be able to use my iPhone with iTunes now?