While attempting to update Microsoft Office 2011 for Mac, you might have encountered a popup asking you to quit SyncServicesAgent. However after going to the activity monitor to quit it, you will notice that the service actually restart automatically. This effectively prevent you from updating your Microsoft Office 2011 for Mac.
Here the solution, go to /Applications/Microsoft Office 2011/Office and delete the SyncServicesAgent.app found in the folder. Do not worry about deleting it as after the update, a new copy of SyncServicesAgent.app will be created. If you are worry, you can rename it to something else.
Hopes this helps.