Does he have an IEP? The school could do a social skills curriculum with him. What about organizational ability and staying on task? Those are other things an IEP could help with. It would be in the "Other Health Disability" category. (and no, despite what the school may tell you, he does not need to have failing test scores or grades, the ADHD just has to have an impact on him academically,f or instance he loses his work, isn't listening or participating in class, or completes work more slowly than the other kids.
We accelerated DD with ADHD, she is now in middle school, and it's hard to say if it was a good or bad choice. Her executive functioning ability is impaired and I need to have numerous communications every week back and forth with her special ed teacher to figure out what work is missing. It took her a long time to figure out she can't be tardy to every class. Without the IEP, she would be in big trouble. So sometimes I think we should have given her an extra year in elementary school but how do you weigh boredom vs. these other skills. She is not behind socially and has plenty of friends, although she claims sometimes that she feels more comfortable with kids in lower grades (i.e., kids that are actually her age). And she'll complain about the grade skip. We didn't know about the ADHD when she was accelerated. If I had known, I probably would have done things differently.
In terms of your situation, is there another class with a different group of boys? A different school? Can the teacher help facilitate him making some friends? If all else fails, I would probably pull out and homeschool, at least temporarily, and try to form friendships with other homeschoolers. My DS's social skills aren't the best (mostly because he withdraws) and he had few friends when placed in a "normal" classroom but now that he is in a program for highly gifted, there are several boys he has a connection with. So what looks like poor social skills may in part be that he just feels like he doesn't fit in (because he doesn't). If you can't get an IEP or a social skills group, you could see if there is a private speech-language pathologist who can work with him on back and forth conversations, listening to the other person even if you're not interested, etc.
