Tons of options on *A if there is availability:
2 segments
- PHL-FRA-JNB (US/LH) would be the simplest route
- EWR-SIN-JNB (SQ) would be nice if you can score this one
3 segments
- PHL-LAX/SFO-SIN-JNB (US/SQ)
4 segments:
- PHL-LAX/SFO/JFK-NRT-SIN (US/UA)
- PHL-LAX-BKK-SIN-JNB (US/TG/SQ)