UA 53 then UA 3752 at Dulles
Zurich → Washington → Oklahoma City
Timetable, Washington time
15:30UA 53 from Zurich at the gate
09:40UA 3752 to Oklahoma City leaves the gate
18 h 10 apart on the timetable, overnight
UA 3752 leaves 18 h 10 after UA 53 arrives on the timetable: more than half a day, so not a connection we count.