If Ainge can't make a substantial trade involving Lee's contract, I think there are other ways to make use of his contract. Ainge should be looking to consolidate the roster and/or adding a player(s) to the roster who a better fit than Lee beyond this year.
Here are two ideas:
Idea #1:
TO BOS: Noah
TO CHI: Gordon, 2nd round pick from NO (protected so it likely doesn't convey)
TO N.O: Lee, Moore, 2nd round pick from BOs (non-philly)
Pretty simple. Noah is injured which allows Bobby Portis to enter the Bulls rotation permanently. Chicago is swapping Noah's expiring for Eric Gordon's while adding more scoring for a playoff push. The Pelicans get Lee, Moore, & a 2nd rounder to compensate them for Gordon (particularly his scoring). The Celtics clear their log jam at PF/C by getting an injured player. Next year IF BOTH PLAYERS ARE HEALTHY I'd prefer Noah>Lee anyday...
Trade #2:
TO BOS: Noah, Anderson
TO CHI: Gordon
TO N.O: Lee, Jerebko, Sully, 2nd round pick from BOS (non-philly), 2nd round pick from CHI
Same logic from trade #1 applies. The Bulls take Moore out of the deal & add a 2nd round pick that isn't protected. The Celtics swap Sully & Jerebko for Ryan Anderon.
Disclaimer: I'm putting Sully in my proposals for the simple fact that he is on an expiring contract. However, we could easily swap him with Olynyk and make the trades work (maybe take back our 2nd rounder since the Pelicans would get another full year of K.O before having to re-sign him)