Quickly tell iTunes to sync your iOS devices with a shortcut.
Open up System Preferences, go to Keyboard, Keyboard Shortcuts.
Click the + symbol at the bottom and a dialog will appear.
- Application: iTunes
- Menu Title: Sync “TheNameOfYouiOSDevice” (Careful: Apple uses smart quotes! In my case it is “zPhone”. Shortcut on US keyboards is ⌥[ and ⇧⌥[)
- Keyboard Shortcut: ⌘S (or something you might remember quite easily)
Click on Add and now you’ll be able to sync your iPhone using ⌘S. (When the iPhone is highlighted in the left sidebar!)