Silva is slated to face Sonnen this summer, though a date has yet to be determined for their fight.
During his most recent outing, a middleweight title eliminator in Chicago on Jan. 28, Bisping lost by unanimous decision to Sonnen.
Boetsch, a former light heavyweight, has won three fights in a row since making his middleweight debut in May 2011.
But it was his come-from-behind TKO victory Feb. 26 over former top middleweight contender Yushin Okami that led Boetsch (15-4) to ask UFC officials for another high-profile opponent.
The fighter Boetsch targeted was Bisping, who also has competed at 205 pounds.
Barao (28-1) has not lost a fight since his mixed martial arts debut on April 14, 2005. He is 5-0 inside the Octagon.
Hougland (10-4) has won nine in a row.
Franklin McNeil covers mixed martial arts and boxing for ESPN.com. Follow him on Twitter at www.twitter.com/Franklin_McNeil.