Yes, short but intense rides will help prepare you for long endurance events.
Several years ago Alberto Salazar won the New York City marathon with the 2nd fastest time ever by an American and it was his first. His longest prior run was 15 miles which was totally counter to all the training rules that say you need several at 20-22 miles. The differewnce was most of his training was for short distance track work that involved intense speedwork.
So you can do a century by training hard for the time you have. Just remember to back off the speed when you do the century.