Sanchez scored 80 times in 166 appearances for the Gunners before arriving at Old Trafford in the middle of the 2017-18 campaign, with Armenian attacker Henrikh Mkhitaryan moving in the opposite direction.
According to ESPN, Wenger had wanted to bring Martial to the Emirates Stadium but was quickly informed by the Red Devils that the France international was not for sale.
The 24-year-old was linked with a move away from Old Trafford during Jose Mourinho's time in charge, having struggled to win the trust of the Portuguese head coach.
The former Monaco youngster has been a key player under current boss Ole Gunnar Solskjaer, though, and has scored 16 times in 34 appearances while operating as a centre-forward this term.
Sanchez, meanwhile, has managed just five goals in 45 outings for the 20-time English champions in all competitions and is currently on loan at Inter Milan.