2-Azetidinone

May 2026 Beta-lactam.svg 150px 2-Azetidinone β-Propiolactam; Azetidin-2-one; 2-Azacyclobutanone 930-21-2 136721 120480 C1CNC1=O 1S/C3H5NO/c5-3-1-2-4-3/h1-2H2,(H,4,5) MNFORVFSTILPAW-UHFFFAOYSA-N 3 5 1 1 2-Azetidinone is a chemical compound with the molecular formula C3H5NO. It is the simplest β-lactam and it forms the central core structure of the β-lactam antibiotics and certain cholesterol medications.PubChem 2-Azetidinone https://pubchem.ncbi.nlm.nih.gov/compound/136721 2026-05-22 pubchem.ncbi.nlm.nih.gov en Chemical structure The molecular structure of 2-azetidinone features a highly strained four membered ring containing three carbon atoms and a nitrogen atom, with a carbonyl oxygen which is double bonded to the carbon position adjacent to the heteroatom. Because of the significant ring strain inherent to a four-membered geometry, the amide bond within 2-azetidinone is considerably more reactive toward nucleophilic attack than a typical acyclic amide. Synthesis The synthesis of 2-azetidinone is primarily achieved through ring-closure reactions. The Staudinger synthesis, a [2+2] cycloaddition, reacts an imine with a ketene to form the four-membered core.Cordero F. M. Giomi D. Machetti F. Synthesis of 2-Azetidinones via Cycloaddition Approaches: An Update Reactions 2024 5 3 492–566 10.3390/reactions5030026 free The Gilman-Speeter reaction provides an alternative, using a Reformatsky reagent to achieve cyclization. Reactivity The molecule’s reactivity is driven by its severe ring strain of approximately 26 kcal/mol. This strain prevents the nitrogen lone pair from fully delocalizing into the carbonyl group, rendering the carbonyl carbon highly electrophilic and susceptible to nucleophilic attack.Jarrahpour A. Zarei M. Synthesis of Novel N-(4-Ethoxyphenyl) Azetidin-2-ones and Their Oxidative N-Deprotection by Ceric Ammonium Nitrate Molecules 2007 12 10 2364–2379 10.3390/12102364 free 17978763 6149079 Medical applications The 2-azetidinone ring is the primary pharmacophore in β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems. These compounds function by binding to bacterial transpeptidase enzymes, effectively inhibiting cell wall synthesis. Additionally, the derivative Ezetimibe utilizes the 2-azetidinone scaffold to inhibit intestinal cholesterol absorption. References Category:Lactams Category:Azetidines