I'm not sure where you are flying from/to.
S7 flights from Western Russia to Far East usually connect in OVB (e.g. DME-OVB-VVO/KHV)
oneworld usually has plenty of reward seats DME-IKT on S7, we flew there last summer for 12500 Avios OW per person.
Stop in IKT for a few days and take a side trip to lake Baikal (train or bus).
From there, there are direct flights to mainland China (e.g. IKT-PEK)