There are 3 chiral centers and an lactam ring in the 4AA structure, which is the focus and difficulty of 4AA synthesis. Early synthesis work began with the selection of suitable and inexpensive chiral sources from natural products for stereocontrolled synthesis. Later, in order to meet the needs of a large number of prepared Chemicalbook, people carried out research on semi-synthesis using penicillin and cephalosporin as raw materials. In recent years, the total synthesis of 4AA has become more active, especially with the development of asymmetric synthesis research, many chemists have tried to apply asymmetric synthesis methods.