Flying from Bangkok to Shanghai non stop and then from Beijin to Los Angeles US with one stop?

I am US citizen and traveling as follow:

Country A: Thailand
Country B: China
Country C: The United States

I would like to know if I could apply for 144-hours visa free. I would have to move from shanghai to Beijing by train and then take my flight in Beijing going to lax, this flight has a stop in CTU (Chengdu Shuangliu International Airport) Can I apply to visa free?
Thank you