The synthesis of cis-N-[a-carbobenzyloxy-b-(p-hydroxyphenyl)ethyl]-3-phthalimido-4-styryl-2-azetidinone is described. We have found that the electron-rich Schiff bases can afford the cis-b-lactam ring even in the presence of the free hydroxyl functions. The mechanisms of cis and trans-b-lactam ring formation are discuss...

the synthesis of cis-n-[a-carbobenzyloxy-b-(p-hydroxyphenyl)ethyl]-3-phthalimido-4-styryl-2-azetidinone is described. we have found that the electron-rich schiff bases can afford the cis-b-lactam ring even in the presence of the free hydroxyl functions. the mechanisms of cis and trans-b-lactam ring formation are discussed. the discussions are consistent with the recent publications.

The Advanced Expert System (AES) was used in conjunction with the VITEK 2 automated antimicrobial susceptibility test system to ascertain the b-lactam phenotypes of 196 isolates of the family Enterobacteriaceae and the species Pseudomonas aeruginosa. These isolates represented a panel of strains that had been collected from laboratories worldwide and whose b-lactam phenotypes had been character...

b-Lactam or azetidin-2-one is an important structural motif of the penicillin, cephalosporin, carbapenem, and carbecephem classes of antibiotics.1 Naturally occurring as well as synthetic monobactams, such as nocardicins and tabtoxin, are also known for their unique antibacterial activities.2e4 Besides their importance as the key structural component of b-lactam antibiotics, b-lactams have been...

Various mechanisms for the alkaline hydrolysis of aza-b-lactam (na), oxo-b-lactam (oa) and thio-b-lactam compounds (sa) were analysed on the basis of PM3 calculations in order to identify potential differences with classical b-lactam antibiotics. Changes in the tetrahedral intermediate were studied via the cleavage of not only the bond between atoms at 7 and 4 as in classical b-lactam antibioti...

The enzymatic ring-opening copolymerization of ε-caprolactone (ε-CL) and β-lactam by using Candida antarctica lipase B (CAL-B) as catalyst was studied. Variation of the feed ratios of 25:75, 50:50, and 75:25 of ε-CL/β-lactam was performed. The products contain poly(ε-CL-co-β-lactam) and the homopolymers of poly(ε-CL) and poly(β-lactam). The structure of the copolymers was determined by MALDI-To...

INTRODUCTION .......................................................................................................................................................547 GENERAL ASPECTS OF b-LACTAM COMPOUNDS........................................................................................548 BIOSYNTHESIS OF PENICILLINS AND CEPHALOSPORINS: AN OUTLINE.............................................

The principal cause of bacterial resistance to penicillin and other b-lactam antibiotics is the acquisition of plasmid-encoded b-lactamases, enzymes that catalyze hydrolysis of the b-lactam bond and render these antibiotics inactive. Clavulanic acid is a potent inhibitor of b-lactamases and has proven clinically effective in combating resistant infections. Although clavulanic acid and penicilli...

Over hundred new a priori global/local molecular descriptors that encoded steric, topological, electronic, hydrogen bonding, compositional and hydrophobic properties were generated for 16 b-lactams, and two partial least squares regression models were constructed and cross-validated. These a priori models (Q > 0.80, R > 0.95, SEV < 0.50) are comparable with the previously obtained computed mode...

Background. Skin tests with soluble b-lactams can be used to diagnose immediate and delayed hypersensitivity (HS) reactions to b-lactam antibiotics. Very few studies have been performed with children with suspected b-lactam allergy. In these studies, immediate HS to b-lactams was diagnosed by skin tests in 4.9% to 40% of children. The diagnostic and predictive values of immediate responses in s...