For those having troubles syncing a Google account in a Mac or iPhone for syncing the calendar, here goes a tip:
open Calendar, and go to Calendar > Add Account > Add CalDAV Account. Set Account Type = Manual and set Server Address = www.google.com, and use your Google User Name and Password.
Worked like a charm for me as my Google account didn’t want to validate on my Mac and sync was broken. On my iPhone I was still using the deprecated exchange service. Changed all to a standard CalDAV service with http://www.google.com as server address and all worked like a charm. Thanks Ben Blazak!