The Black Eagles have reached an agreement with the Portuguese giants to loan Talisca on a two-year deal with an undisclosed buyout clause.
Turkish football journalist Gökmen Özdemir was the first to break the news of Besiktas reaching an agreement with the 22-year-old.
NTV Spor are now also reporting that a deal has been reached and that Talisca will arrive in Istanbul over the next few days to undergo a medical and complete the move.
Per the source, the Championship outfit were on the verge of completing the move in what would have been a marquee signing for the new Chinese owners – Fosun.
The Brazilian midfielder scored twice in the Champions League last season and made 21 appearances in the league last season.
Talisca will play Champions League football this season if his Besiktas move goes ahead as planned.