A hole in the clouds - the way to discipline?

Thomas loves to disobey. Not listen to instructions. We can't say no a hundred times anymore, bribe him immensely to come to the dinner table, or pull our hair out as we try to get him to stop pinching Nathan after he gets teased or when something is not given to him - curse you and love you, Lego car wheels! We need to be firm when telling Thomas no. Keep a steady tone, no need to raise voices, but say the direction consistently until it's obeyed. Facial expressions should say you mean business. He can be told to go brush his teeth and follows that - he has demonstrated that several times. If Thomas develops discipline as fast as he develops reading or memorisation skills, he could really put his time to good use. My goal for Thomas is to stand and recite something he's memorised to his peers in grade 6.