I'd first suggest, not turning your back on him. I learned this very quickly with Twin Boys
We are going through something similar with our Twins. Sounds like the same age as your Boy. I know the frustration, end of your rope, throw you arms up nearly every second in frustration and the most common phrase, doesn't listen and then wonders 'why' he got into trouble. Yep, been there and still am. Hang in there it can only get better
Watching / View / Attention:
I know it is hard, but if he knows you are watching, maybe he is inclined not to do something.
Sounds like he wants attention, be noticed, recognized. A basic human need and desire. He will do whatever to get the attention, even if negative and punishable. Make sure you give him eye contact when he speaks with you. Ask him to do the same with you when you speak with him. He will fast learn that he has your undivided attention and vv when you need his attention.
Communication / Hearing Problems
Maybe he doesn't understand the "don't do x" as "do x" ?
Does he or could he have Hearing Problems? Our DS-L had and still does have hearing problems. Makes communication with him and him with us, nearly impossible and frustrating at times. No it is not to early for hearing tests. Our Twins will be 5 in Mid-Summer.
Boundaries / Punishment
If he is going to do these, than make him clean it up. Dont' help him. Rule around here and anywhere we go, "you make the mess, you clean it up."
Testing the boundaries. What he can and cannot get away with.
As someone suggested to me, what is something that will really get his attention and not cause him to do 'x' again. DH & I thought about it and what we came up with has worked.........so far.
As for priviledges, what does he like to do? Play outside, going to the beach, going to the park, going to where? What does he like to do (besides push your buttons - ha, ha
) Swimming, Riding a bike, Playing Ball, Going to a game (Baseball, Football, Soccer)? Start taking away a priviledge at a time. Someone suggested this to us.......that is what is working so far. The Boys have to choose from a basket of stuff they like to do and remove something. They know they aren't supposed to do 'x' and if they do, they did the punishment to themselves.
Who are his playmates? Could he have some Bullies for Playmates you aren't aware of? Both our Boys have had problems with Bullies at school. He may view their behavior as something to try or he likes it. Hence, why you are having destructive behavior at home.
Good Luck