Novel 2-aminoimidazolone derivatives were synthesized. Most compounds displayed strong anticancer activities against human carcinoma cells in vitro. Compounds 8a, 8b and 8j exhibited optimal activity superior to 5-FU in most cancer cells tested. Especially, the IC50s of 8b (12.6–21.5 μmol/L) against five tumor cells were 1–4 fold less than those of 5-FU (18.4– 56.1 μmol/L) in vitro. Furthermore, compound 8b could induce SMMC-7721 cell apoptosis ...