iPhone sync freezes on Calendar

I had this happen on my previous iPhone when syncing with Outlook. Not sure this will help, but in my case I has some recurring appoinments that iTunes didnt like. When it got to that point, it hung.

I would try backing up the Calendar and trying a brand new calendar, with a test appointment. If that syncs fine, then try copying your backup entries onto the new Calendar. There may be something corrupt in your old calendar.

That's the best I can do with such short notice....

I had trouble syncing my calendar when I got my first iPhone not sure if this is your issue but ANY recurring calendars dates need an end date ( I had birthdays recurring with obviously no end dates and the iPhone will not sync with that)
Put end date at 30 years all is fine.....

I would suggest backing up your Calendar and wiping it out to start with a fresh new one, and with a couple of test appointments. That way you can rule out any corrupt data in your Calendar.