First synthetic access to 6-(methylene)oxapenems: A new class of β-lactamase inhibitors

Article abstract of DOI:10.1055/s-1992-26314

The first synthetic route to racemic 6-(substituted methylene)oxapenems, an interesting new class of β-lactamase inhibitors, is described. In spite of their low hydrolytic stability, even the unprotected acids 9 and 10 can be isolated as their sodium salts. The 6-(unsubstituted methylene)oxapenem 7e, however, is unstable and decomposes under the conditions of its formation.