Frankfurt > Shanghai > Munich

No, your itinerary is a round trip and not a transit. The basic rule of 144 hour visa free transit clearly says that the immediate points before and after your mainland Chinese destination have to be in two different countries or eligible territories. Eligible territories are Hong Kong, Taiwan and Macau. However, since you did not mention your citizenship, I will tell you that if you are a German citizen than you can do this round trip because German citizen can enter China visa free for stays of up to 15 days. So, if you are a German citizen you can travel based on the presented itinerary, but if you are a citizen of some other country that requires a visa to enter China, you will have to obtain a Chinese visa in advance or to alter your itinerary to be in line with the regulations of 144 hour visa free transit.