Tehran is 4.5 hours behind Shanghai
Best overlap: 1:00 PM to 6:00 PM in Shanghai is 8:30 AM to 1:30 PM in Tehran.
If you set up a recurring sync, 1:00 PM to 6:00 PM in Shanghai (8:30 AM to 1:30 PM in Tehran) is the natural home for it. Tehran is 4.5 hours behind Shanghai, which gives you a solid 5-hour window. Book earlier in it and neither side is rushing.