(1S)-hydroxyalkyloxapenem-3-carboxylsyrer og deres anvendelse som betalactamasehæmmere

The invention relates to 1-oxapenem-3-carboxylic acids of the following structure: in which R , R , R and R independently of one another denote pharmaceutically acceptable groups which are bonded to the remaining part of the molecule via carbon-carbon single bonds and which have one to 10 carbon atoms, and in which R denotes H, alkyl or acyl having up to 10 carbon atoms or an inorganic acid radical. These compounds, and also their pharmaceutically acceptable salts, esters and amide derivatives, are particularly useful beta-lactamase inhibitors. The invention furthermore relates to pharmaceutical preparations containing these compounds and to treatment processes, as well as to processes for the preparation of such compounds.