Washington, D.C. is 2 hours behind Brasília
Best overlap: 10:00 AM to 6:00 PM in Brasília is 8:00 AM to 4:00 PM in Washington, D.C..
For the smoothest call, aim inside 10:00 AM to 6:00 PM in Brasília, i.e. 8:00 AM to 4:00 PM in Washington, D.C.. The overlap is wide at 8 hours, so you can protect mornings for deep work and still find plenty of meeting time. For part of the year the maths changes: Washington, D.C. observes daylight saving, Brasília does not, shifting the overlap by an hour.