UA 2433 then B6 8353 at Boston
Newark → Boston → New York JFK
Timetable, Boston time
17:27UA 2433 from Newark at the gate
06:00B6 8353 to New York JFK leaves the gate
12 h 33 apart on the timetable, overnight
B6 8353 leaves 12 h 33 after UA 2433 arrives on the timetable: more than half a day, so not a connection we count.