The problem you and your son are facing is very common. Remember he is 5 and full of energy, sadly most of his day is spent having to sit still. My son experienced a similar problem at that age. I suggested to his teacher to allow him to stand up and stretch periodically during periods of 45 min.s or more that he would have to stay seated. It could be that your son has a very active imagination, which is wonderful, allowing him to stand and strech will help him regain focus and remain on task. One other thing to consider is whether or not he is bored with the lessons being taught. If this is the case, he may require a more advanced class.

you can either try apositive and negative enforcement let your child know if he behave well in class he'll get something good or if he doesnt behave well in school he will not get anything.

I agree with Cyndir that chattering 5 and 6 year olds can be a problem in  class. But we must remember that socialization and vocalization are ways young children cement their ideas.  In most K- 2 classrooms students don't sit for 45 minutes! Students are up and moving from seats as they work in small groups, back to tables/ desks, to quiet places around the room and to large group gathering spaces. The rooms that I have observed are in consent motion of movement.  Bordom? Doubtful. That's just an adult excuse. Children are most creative at learning, inventing or exploring.   Ask the teacher to identify times when your son is too chatty.  Is it at seat work time? Does he disturb his neighbors as they are working?  Do his neighbors ask him nicely to work quietly? Does he respond to his peers request in a positive way?  Is he chatty in small group or large group situations.  Maybe he is just trying to share his wonderful ideas and needs some positive guidance about how and when it is appropriate to speak.  Talk with the teacher to see if there is a behavior chart.  A simple Red Light- Green Light  System works well because it is a visual reminder of how a child's day/ behavior choices are going.  Also sometimes a "talking ball" helps a chatty child remember  when it's okay to talk.  Children love to hold a ball when they speak and it helps the listeners be more conscience about when its time for them to listen and not talk over each other.  Either way... honest and sincere dialog with your son's teacher is important.  Work together to devise a plan to help your son make smart choices.  Positive reinforcement with little ones always works better then a take away punishment. Teaching our children how and when to communicate ideas is a very important skill that young children often need guidance with. Devise a positive plan with your child and his teacher. The sooner he learns how to adjust his behavior the better his educational experience will be.  Save the take away punishments for the REALLY bad choices!

I wouldn't be too drastic since you are dealing with a problem that your child may not be able to control as easily as an older child.  Perhaps the child needs more opportunities to expend physical energy.  Ask his teacher to have him/her run around the building each time as a result of the disruption and see if that helps.