It's time, Shannon, when you can STILL do something about it, as soon you won't have much influence at all: adolescents get very independent way too quickly for us parents to be only frustrated.
So, what I'd do, I'd set up a schedule of obligations that need to be accomplished: work passed in in time; and benefits of it: did good during the week, you get your videogame/TV show, taken to the movie, get out with friends for 4 hours, whatever he likes to do a lot. If the work is not passed in and you find it out: ask HIM what he will miss then, give him a CHOICE, so that he does not feel the confrontation like in a battle where he is on one side of the line and you adults threatening him on the other side, this does not work very well with your deep relationships, as he hates to be ordered around. So, let him chose what he will miss this week(end), and go with HIS plan for two weeks. Then, if the missing work will still happen, say :sorry, son, this does not seem to be working, I need to help you out and give you a next suggestion: we will try this way now: you miss ..... whatever is awfully dear to him. Go with it for another two weeks. He will definitely miss SOME works but there should be much less of those. parallel to this schedule, softly and surely lead your conversations to the need of these arrangements, as he needs to learn to UNDERSTAND why it is important for him to do the schoolwork well. Seek for examples, what can be benefits of goo education in life. If he says (typical teenager's excuse) "the work is stupid, I do not gain a thing of it and will never use chemistry in my life, so why do I need it now? and anyways, the teacher is just dumb and I hate him..." start teaching him that through obeying the 'dumb' teacher (you cannot convince him that it is not true, don't even try, it won't work!!!), he learns how to work with 'dumb'people. what if he gets a great job in life, the one he likes a lot, but the BOSS is plain dumb! If he disobeys the boss, he will lose a great job. To obey a stupid boss seems stupid also, but what a gain: good salary, and an interesting job ...SO, sometimes we need to ADJUST, not obey. It is like a maze, to walk through: you cannot ignore this teacher, but you CAN meet some of his expectations to not spoil grades and good mood, and not loose the weekend activities at home, and this is well worth it. Shannon, this is a slow process, you need to be patient and CREATIVE but A LOT depends on you now, how you teach him to work through things in life. He may have an important meeting when he is 20, and miss the moment and lose half a million he was about to win! So, preciseness with time is important to learn, and this homework situation is a good exercise to practice this skill.
Also, always stay on his side: do not confront him openly: first say something good, and then point out what is not QUITE right and needs to be worked on, yet you are always WITH him to help and support.This gives him a feeling of self-confidence, not frustration and the feeling of the generation gap: "they just don't understand" thingie that leads the kids to gangs, where he has all the respect that he so badly needs...
Good luck to you both!
Merike