Hey K. S,
I feel ya, I have 4 y/o& a 9 y/o girl who are the same way.
I just started reading the amazing book "Parenting with Love & Logic" if you have the chance you should try to pick up a copy.
I have tried some of the suggestions and they actually work...
re-wording instead of tell or even asking give him choices
"would you like to clean up your room before snack or after?"
that way it puts him in charge , it give him choices...if he says he doesn't want to clean his room at all you say .....
"well then after you clean your room you are invited to join me for snack."
the book is really great & has help my family in just the 3 days since I have started it.
A little about me:
I am a 37 y/o , married to military,SAHM of 4 y/o & 9 y/o girls