Azetidines are an important class of saturated four-membered nitrogen-containing heterocyclic compounds. The research hotspots related to this structure mainly focus on two aspects: one is the research of pharmaceutical chemistry; the other is related to chiral azetidines, using rigid azetidine compounds as chiral ligands for asymmetric catalytic reactions. Many nitrogen-containing heterocycles play important roles in drug structures, and in many cases small structural changes can improve ligand selectivity and pharmacokinetic properties.