Brasília is 6.5 hours behind Tehran
Best overlap: 3:00 PM to 6:00 PM in Tehran is 8:30 AM to 11:30 AM in Brasília.
If you set up a recurring sync, 3:00 PM to 6:00 PM in Tehran (8:30 AM to 11:30 AM in Brasília) is the natural home for it. Around 3 hours of overlap is enough to work comfortably, as long as meetings don't drift to the end of one team's day.