Timberlake, who has a supporting role in the film that stars Carey Mulligan, teamed up with Mulligan's husband and Mumford & Sons frontman Marcus Mumford for a collaboration on the film's soundtrack.
"OK I can tell you this: There's a Coen brothers film coming out soon that I was lucky enough to work with Oscar Isaac and Carey Mulligan," Timberlake told Capital FM. "And coincidentally I did work with Marcus Mumford on the soundtrack, so I became very good friends with them."
"Marcus and myself, we all kind of worked on the music together. And I don't know any other world where we would have the opportunity to collaborate like that, but it was so much fun. So not only will that be a great movie, but the music to it will be fantastic."
Timberlake returned to making music with "Suit & Tie," his first single since 2007, ahead of the release of a new album, The 20/20 Experience.
Mumford, with T Bone Burnett (O Brother, Where Art Thou?, Crazy Heart), is producing the soundtrack for Inside Llwelyn Davis, a film about a singer-songwriter in 1960's New York, loosely based on Dave Von Ronck's memoir The Mayor of MacDougal Street.
Mumford is coming off a good year, with his group's sophomore album, Babel taking Album of the Year at the Grammys earlier this month.
Boston schools pull out free condoms over wrapping complaints
Millions of Getty images now available for free via embed tool