Dembele moved to Camp Nou in the wake of Neymar's transfer to PSG, costing an initial fee of £100m, but has spent much of his time there injured and when he has played, his performances have been deeply disappointing.
Barcelona have numerous striking options for the season ahead thanks to the addition of Trincao, the return of Philippe Coutinho from his loan at Bayern Munich and the continued emergence of Ansu Fati.
Ronald Koeman has also been keen to add Memphis Depay from Lyon, meaning there is the chance that Dembele may be surplus to requirements.
But Barcelona will not be open to loan deal simply because they need to raise funds now to make acquisitions and they will demand a significant fee, likely £90-£100m, to recoup their losses.
United are looking at alternatives after baulking at Jadon Sancho's asking price and it's clear that they would do the same with Dembele. Liverpool, meanwhile, have already added Diogo Jota as back-up to their front three.
It is unclear whether in this market and with Dembele's chequered recent history either would be willing to part with such a big fee for the former Dortmund player.
As such, it would take a significant shift from either side of the deal in order for anything to happen before the window closes at the beginning of next month.