UA 1232 then DL 5679 at Boston
Denver → Boston → Louisville
Timetable, Boston time
15:32UA 1232 from Denver at the gate
10:25DL 5679 to Louisville leaves the gate
18 h 53 apart on the timetable, overnight
DL 5679 leaves 18 h 53 after UA 1232 arrives on the timetable: more than half a day, so not a connection we count.