In a word no.
The policy is use it or lose it
However there are people who have, myself included, used weekly syns. You have 105 to use across the week and you deduct from that total so essentially it achieves the same thing. It was ok for me but I wouldn't do it all the time.
It's not recommended officially but I know that some consultants use the concept to help those who maybe work funny shifts and don't keep a usual timetable.