Abstract:The review reports a short biography of the Italian naturalized chemist Hugo Schiff and an outline on the synthesis and use of his most popular discovery: the imines, very well known and popular as Schiff Bases. Recent developments on their "metallo-imines" variants have been described. The applications of Schiff bases in organic synthesis as partner in Staudinger and hetero Diels-Alder reactions, as "privileged" ligands in the organometallic complexes and as biological active Schiff intermediates/targets have been reported as well.
Since the 1940s β-lactam antibiotics have been used to treat bacterial infections. However, emergence and dissemination of β-lactam resistance has reached the point where many marketed β-lactams no longer are clinically effective. The increasing prevalence of multidrug-resistant bacteria and the progressive withdrawal of pharmaceutical companies from antibiotic research have evoked a strong reaction from health authorities, who have implemented initiatives to encourage the discovery of new antibacterials. Despite this gloomy scenario, several novel β-lactam antibiotics and β-lactamase inhibitors have recently progressed into clinical trials, and many more such compounds are being investigated. Here we seek to provide highlights of recent developments relating to the discovery of novel β-lactam antibiotics and β-lactamase inhibitors.
[formula: see text] Conrotatory ring closure of 1-halo-3-aza-4-alkyl-1,3-dienes in refluxing toluene gives rise to 3-halo-4-aryl-2-azetidinones in satisfactory yields. Dehalogenation of the resulting beta-lactams by tris(trimethylsilyl)silane furnished 3-unsubstituted azetidinones, valuable intermediates in the synthesis of biologically active compounds.
The introduction of antibiotics to treat bacterial infections either by killing or blocking their growth has been accompanied by the development of resistance mechanism that allows the bacteria to survive and proliferate. In particular the successive series of β-lactams have selected several generations of β-lactamases including ESBLs, AmpC β-lactamases, KPC carbapenamases in Enterobacteriaceae, the metallo β-lactamases VIMs and IMPs, and very recently the threatening NDM-1 that confers resistance to virtually any clinically used antibiotic. The increasing use of carbapenems due to the spread of resistance to other existing antibacterial agents has facilitated the spread of resistance, especially in Acinetobacter spp. due to OXA- and metallo-carbapenemases. The pharmaceutical industry, that abandoned this field at the end of the nineties, is now trying to recover by developing some novel β-lactam antibiotics and novel β-lactamase-inhibitors, the latter to be used in combination with new as well as seasoned β-lactam antibiotics. This article provides a survey of patent and scientific literature for β-lactamase inhibitors discovered in the period 2006-2010.
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