Parenting young children can be the most frustrating thing you ever do in your life. However, it also is the most important thing you will ever do. Helping them form their behaviors, their boundaries and their ability to get along in this world is invaluable. All of our children have unique and individual emotional makeup that forms their personalities.
If you have not had his pediatrician check him over with the specific goal in mind of ruling out physical issues that might be affecting his behavior, do so to make sure there is not a contributing medical cause. If that is eliminated, then we encourage you to look into some possible programs that work specifically with young children who have continued to fail in spite of different approaches to modify their behaviors. Your frustration level, his and his teacher's are not making things better. In fact it is more difficult for all of us to control our behaviors when we are frustrated.