DL 2868 then UA 4749 at Detroit
St Louis → Detroit → Chicago O'Hare
Timetable, Detroit time
12:52DL 2868 from St Louis at the gate
10:48UA 4749 to Chicago O'Hare leaves the gate
21 h 56 apart on the timetable, overnight
UA 4749 leaves 21 h 56 after DL 2868 arrives on the timetable: more than half a day, so not a connection we count.