Since SQ is going 77W for SFO-HKG-ICN, you're not likely to be able to find that routing for an award. (You're not going to be able to redeem for business class on the LAX-SIN non-stop either.)
Far easier is LAX-NRT-SIN. Search LAX-SIN
using the All Nippon Airways website, find your availability, and then call US and request those flights.