beta-Lactamase inhibitors derived from N-tosyloxy-beta-lactams

Syntheses and studies of new forms of N-sulfonyloxy β-lactams as potential antibacterial agents and β-lactamase inhibitors

The synthesis of a small library of N-sulfonyloxy-2-azetidinones is reported and the preliminary results of the investigation of the biological activity of these molecules are discussed. These new multi-electrophilic β-lactams ('electrophilic bombs') display unexpected selectivity in their antibacterial activity and β-lactamase inhibitory activity.

Biosynthetic concepts for the production of β-lactam antibiotics in Penicillium chrysogenum

Industrial production of β-lactam antibiotics by the filamentous fungus Penicillium chrysogenum is based on successive classical strain improvement cycles. This review summarizes our current knowledge on the results of this classical strain improvement process, and discusses avenues to improve β-lactam biosynthesis and to exploit P. chrysogenum as an industrial host for the production of other antibiotics and peptide products. Genomic and transcriptional analysis of strain lineages has led to the identification of several important alterations in high-yielding strains, including the amplification of the penicillin biosynthetic gene cluster, elevated transcription of genes involved in biosynthesis of penicillin and amino acid precursors, and genes encoding microbody proliferation factors. In recent years, successful metabolic engineering and synthetic biology approaches have resulted in the redirection of the penicillin pathway towards the production of cephalosporins. This sets a new direction in industrial antibiotics productions towards more sustainable methods for the fermentative production of unnatural antibiotics and related compounds.

Enantioselective synthesis of alpha-amino acids from N-tosyloxy beta-lactams derived from beta-keto esters

A novel synthetic sequence has been developed to convert simple beta-keto esters into enantiomerically enriched alpha-amino acids. The key features of this sequence include the addition of azide to the C3 position of beta-keto ester derived N-tosyloxy-beta-lactams through a concomitant nucleophilic addition/N-O bond reduction reaction, a mild CsF-induced N1 benzylation of alpha-azido monocyclic beta-lactams, the preparation of alpha-keto-beta-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-beta-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-beta-lactams is reported.