New synthetic siderophores and Their β-Lactam conjugates based on diamino acids and dipeptides
摘要:
Linking of siderophores to antibiotics improves the penetration and therefore increases the antibacterial activity of the antibiotics. We synthesized the acylated catecholates and hydroxamates as siderophore components for antibiotic conjugates to reduce side effects of unprotected catecholate and hydroxamate moieties. In this paper, we report on bis- and tris-catecholates and mixed catecholate hydroxamates based on diamino acids or dipeptides. These compounds were active as siderophores in a growth promotion assay under iron limitation. Most of the conjugates with beta-lactams showed high in vitro activity against Gram-negative bacteria especially Pseudomonas acruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia mareeseems and Stenotrophomonas maltophilia. The compounds with enhanced antibacterial activity use active iron uptake routes to penetrate the bacterial outer membrane barrier, demonstrated by assays with mutants deficient in components of the iron transport system. Correlation between chemical structure and biological activity was studied. (C) 2002 Published by Elsevier Science Ltd.
A General Method for the α-Acyloxylation of Carbonyl Compounds
摘要:
A simple, one-pot method for the alpha-acyloxylation of carbonyl compounds that proceeds at room temperature in the presence of both moisture and air has been developed. Treatment of a variety of aldehydes and both cyclic and acyclic ketones with N-methyl-O-benzoylhydroxylamine hydrochloride provides the alpha-functionalized product in 69-92% isolated yield. The transformation is tolerant of a wide range of functional groups and, significantly, is reglospecific in the discrimination of secondary over primary centers in the case of nonsymmetrical substrates.
NGCYCLOARTANONE DERIVATIVES WITH ANTICANCER ACTIVITY
申请人:Long Christophe
公开号:US20120077777A1
公开(公告)日:2012-03-29
The present invention relates to a compound of following formula (I):
or to a pharmaceutically acceptable salt thereof, as well as to pharmaceutical compositions including same and to the use thereof as a drug, in particular for treating a proliferative disease such as cancer.
作者:Deborah A. Smithen、Christopher J. Mathews、Nicholas C. O. Tomkinson
DOI:10.1039/c2ob25293g
日期:——
Reaction of cyclic ketones with chiral N-alkyl-O-acyl hydroxylamines leads to the corresponding α-oxyacylated carbonyl compound in up to 89% ee. The levels of asymmetric induction were influenced by solvent polarity, acid strength and, to a lesser extent, temperature. Increasing the steric bulk around the nitrogen atom of the hydroxylamine reagent led to increased levels of asymmetric induction, which was also found to be detrimental to the yield observed for the transformation. Examination of N- and O-substituents along with substrates revealed the scope and limitations of the procedure.
Total synthesis and biological evaluation of (−)-atrop–abyssomicin C
作者:Filip Bihelovic、Ivanka Karadzic、Radomir Matovic、Radomir N. Saicic
DOI:10.1039/c3ob40692j
日期:——
Enantioselective synthesis of a marine antibiotic (−)-atrop–abyssomicinC was accomplished in 21 steps, in 1.8% overall yield (4%, based on the recovered starting material). The key steps of the synthesis are the formation of the functionalized cyclohexane core by an organocatalyzed Tsuji–Trost reaction, the formation of a tricyclic spirotetronate unit by a gold-catalyzed reaction sequence and the
α-Aroyloxyaldehydes: scope and limitations as alternatives to α-haloaldehydes for NHC-catalysed redox transformations
作者:Kenneth B. Ling、Andrew D. Smith
DOI:10.1039/c0cc02456b
日期:——
α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates. Their ability to act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions is described.
Total Synthesis of the <i>Illicium</i>-Derived Sesquineolignan Simonsol C
作者:Jeremy Nugent、Martin G. Banwell、Brett D. Schwartz
DOI:10.1021/acs.orglett.6b01799
日期:2016.8.5
The racemic form of the title natural product 1 has been synthesized by engaging, as a key step, the iodoarene-tethered cyclohexene 22 in an intramolecular Heck reaction to give compound 23. This angularly substituted tetrahydrodibenzo[b,d]furan was elaborated over a further five steps into target (±)-1.