We investigated the role of chromosomal beta-lactamase and the MexAB-OprM efflux system in intrinsic resistance to beta-lactams in Pseudomonas aeruginosa. Determination of the susceptibilities of a series of isogenic mutants with impaired production of the beta-lactamase and the efflux system to 16 beta-lactams including penicillins, cephems, oxacephems, carbapenems, and a monobactam demonstrat...

Recent developments in the chemistry and biology of βlactam antibiotics which culminated with the introduction of several clinically useful classical and nonclassical β-lactams have been most thrilling and highly rewarding. While this review touches upon the historical development of β-lactams and their reactivity in a nutshell, it provides an overview of various aspects of chemical and enzymat...

Mesoporous MCM-41 silicas anchored with sulfonic acid (–SO3H) groups (denoted MSN-SA) via postsynthesis modification are very effective for the Beckman rearrangement. A simple and convenient procedure for conversion of a variety oximes to their corresponding amides and lactams has been developed. The reaction was carried out in the presence of MSN-SA as the catalyst. The best results for conver...

Some new mono-and bis-polycyclic aromatic spiro-beta-lactams and bis-non spiro-polycyclic aromatic beta-lactams have been synthesized from imines derived from anthracene-9-carbaldehyde, 2-naphtaldehyde and a ketene derived from 9H-xanthene-9-carboxylic acid and phenoxyacetic acid by a [2+2] cycloaddition reaction. The cycloadducts were characterized by spectral data, including 1H-NMR, 13C-NMR, ...

Abstract The -lactams and the related -sultams are attractive targets for synthesis because of their central importance in antibiotics such as the penicillins. These heterocycles are of further interest because of their potential as inhibitors of the serine protease class of enzymes, believed to be responsible for diseases such as rheumatoid arthritis and cystic fibrosis. This thesis will des...

From carboxylic acid trifluoromethyl aziridines, halogeno β-lactams were obtained stereoselectively by ring expansion. Different conditions such as radical, organometallic reactions allowed easy and selective access to CF3-β-lactams substituted at the C-3 position.

The ring contraction-lactamisation of anhydrides upon reaction with trimethylsilylazide in the presence an amine catalyst has been studied. Under controlled conditions, 5,- 6- and 8-membered lactams can be generated from cyclic operationally simple procedure. In case ?-lactams, methodology allows for synthesis challenging systems incompatible usual disconnection involving activated carbonyl gro...

beta-lactams are a group of antibiotics with a broad spectrum of both gram-negative and gram-positive coverage. the goal of this study is to evaluate the results from studies regarding ig-e mediated hypersensitivity to penicillin and cross-reactivity with other beta-lactams. review was conducted of both retrospective and prospective studies by searching in pubmed and medline for the original an...