Per Adrian Wojnarowski of Yahoo! Sports, Brooklyn and Boston have discussed a deal that would send The Captain to the Nets for an assortment of rebuilding blocks.
Also from Woj's report:
Woj also mentions Ainge's interest in acquiring combo guard C.J. Watson in a separate deal, but that Brooklyn has rebuked that offer. As many have suggested, Ainge is teetering on a fine line between contending this season and rebuilding completely, but I think it's more accurate to say that if Danny chooses the latter, he's looking to do it quickly. Pierce for parts is a long term solution; if Ainge is going to make the unpopular move of dealing a Celtic icon, he'll have to get more proven pieces that help them win in the immediate future (like a Josh Smith).