Fourth-seeded Canisius (21-11) advanced to the semifinals Sunday to face top-seeded Iona (21-9), which beat Rider 94-71 on Saturday.
Siena (15-17), a No. 5 seed, led 11-6 on a jumper by Imoh Silas, but Canisius led 21-11 on a 3 by Zach Lewis. The lead traded hands six times until Brett Bisping's two free throws gave Siena a 34-33 halftime lead.
Siena led 54-52 at 8:02 in the second after Ryan Oliver and Bisping each hit treys. Chris Manhertz put Canisius up 69-65 with a layup at 1:06, and Baron's layup clinched the game with 16 seconds to play.
Jordan Heath scored 11 for Canisius. Manhertz and Lewis had 10 each, and Manhertz grabbed 11 rebounds.
Bisping led Siena with 22, and Rob Poole had 14.