B6 778 then UA 2400 at Boston
Las Vegas → Boston → San Francisco
Timetable, Boston time
05:00B6 778 from Las Vegas at the gate
18:01UA 2400 to San Francisco leaves the gate
13 h 01 apart on the timetable
UA 2400 leaves 13 h 01 after B6 778 arrives on the timetable: more than half a day, so not a connection we count.