UA 1264 then B6 1734 at San Francisco
Las Vegas → San Francisco → Boston
Timetable, San Francisco time
11:32UA 1264 from Las Vegas at the gatealso AC 3714, AZ 4443, NZ 9240, LH 9415
10:44B6 1734 to Boston leaves the gatealso FI 7830
23 h 12 apart on the timetable, overnight
B6 1734 leaves 23 h 12 after UA 1264 arrives on the timetable: more than half a day, so not a connection we count.