LA 6139 then B6 616 at San Francisco
Boston → San Francisco → New York JFK
Timetable, San Francisco time
23:58LA 6139 from Boston at the gate
22:56B6 616 to New York JFK leaves the gatealso EY 8046, EY 8242, EY 8246, JU 8513
22 h 58 apart on the timetable, overnight
B6 616 leaves 22 h 58 after LA 6139 arrives on the timetable: more than half a day, so not a connection we count.