Carba-2-oxacephem

Cephalosporins are important (f-lactams, but a number of pathogenic microorganisms have developed resistance to these antibiotic compounds. In order to prepare novel antibiotic cephalosporin analogs, I. Chao and co-workers synthesized 1-dethia-3-aza-1-carba-2-oxacephem, which is not a substrate of the inducible 3-lactamase enzyme. The key step of the synthetic sequence was the Barton nitrite ester reaction in which regioisomeric oximino 3-lactams were generated and transformed into the desired product. ... 

Hakimelahi, G. H., Li, P.-C., Moosavi-Movahedi, A. A., Chamani, J., Khodarahmi, G. A., Ly, T. W., Valiyev, F., Leong, M. K., Hakimelahi, S., Shia, K.-S., Chao, I. /Application of the Barton photochemical reaction in the synthesis of 1-dethia-3-aza-1-carba-2-oxacephem a novel agent against resistant pathogenic microorganisms. Org. Biomol. Chem. 2003,1, 2461-2467. 

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