UA 3797 then B6 1534 at San Francisco
Louisville → San Francisco → Boston
Timetable, San Francisco time
22:20UA 3797 from Louisville at the gate
22:10B6 1534 to Boston leaves the gatealso EY 8032
23 h 50 apart on the timetable, overnight
B6 1534 leaves 23 h 50 after UA 3797 arrives on the timetable: more than half a day, so not a connection we count.