The comparable I suppose is the Vatanen-Henrique trade. There was some issue between Vatanen and Anaheim though. I can't remember it exactly, but Vatanen was being shopped around for a while before he was traded.
Maybe the Leafs could get Trouba that way, since there's lots of talk that he could be trade bait, but he'd have to want to play for Toronto, which could be the case but who knows? I can't think of any other D like that who is rumored to be potentially traded.
I don't think they could get a D like that if there is no x-factor, pushing a trade to happen.