title: Intramolecular nucleophilic attack of an ureido group on the beta-lactam carbonyl moiety of penicillins.
mesh_terms: D003500:Cyclization; D004355:Drug Stability; D006827:Hydantoins / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007536:Isomerism; D007700:Kinetics; D010397:Penicillanic Acid; D010406:Penicillins; D013056:Spectrophotometry, Ultraviolet; D013844:Thiazoles / Q000032:analysis
chemical_list: D006827:Hydantoins; D010406:Penicillins; D013844:Thiazoles; D010397:Penicillanic Acid