UA 2647 then DL 5679 at Boston
San Francisco → Boston → Louisville
Timetable, Boston time
16:49UA 2647 from San Francisco at the gate
09:55DL 5679 to Louisville leaves the gate
17 h 06 apart on the timetable, overnight
DL 5679 leaves 17 h 06 after UA 2647 arrives on the timetable: more than half a day, so not a connection we count.