Isolation and structure elucidation of a novel product of the acidic degradation of cefaclor
The acidic aqueous degradation of cefaclor, an orally administered cephalosporin antibiotic, has been investigated. The most prominent peak in the high-performance liquid chromatography profile of a degraded solution of cefaclor was isolated by preparative high-performance liquid chromatography. Mechanistically, the formation of this degradent from cefaclor involves a condensation of two cefaclor degradation products in which both products have undergone contraction from a six-membered cephem ring to a five-membered thiazole ring, presumably via a common episulfonium ion intermediate.
SIGMA-1 RECEPTOR LIGANDS AND THERAPEUTIC USES THEREOF
The present invention relates to the field of medicine. More specifically, the present invention relates to compounds that are sigma-1 receptor agonists and their use for the treatment of central nervous system disorders, including cognitive or neurodegen
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(2021/06/26)
Electrochemical Cross-Coupling of C(sp2)?H with Aryldiazonium Salts via a Paired Electrolysis: an Alternative to Visible Light Photoredox-Based Approach
Photoredox-based C?H bond functionalization constitutes one of the most powerful and atom-economical approaches to organic syntheses. During this type of reaction, single electron transfer takes place between the photocatalyst (PC) and redox- active substrates. Electrosynthesis also involves electron transfer between substrates and electrodes. In this paper, we focus upon electrochemical cross-coupling of C(sp2)?H with aryldiazonium salts and have developed an efficient electrochemical approach to the Minisci-type arylation reaction. The constant current paired electrosynthesis proceeds in a simple undivided cell without external supporting electrolyte, features a wide range of substrates and is easy to scale-up. These results demonstrate that photoredox-based cross-coupling of C(sp2)?H with aryldiazonium salts can also proceed successfully under paired electrolysis conditions, thereby contributing to understanding of the parallels between photosynthesis and electrosynthesis. (Figure presented.).
Jiang, Yang-ye,Dou, Gui-yuan,Zhang, Luo-sha,Xu, Kun,Little, R. Daniel,Zeng, Cheng-chu
p. 5170 - 5175
(2019/11/13)
Isolation and identification of a fluorophore from ampicillin degradation
A fluorescent impurity in ampicillin has been isolated and identified as 2-hydroxy-3-phenyl-pyrazine. The product is formed under acidic conditions similar to those employed in some fluorometric assay procedures. The mechanism of the reaction is proposed to involve cyclization by condensation of the penilloaldehyde of ampicillin. The structure was confirmed by independent synthesis.
Lebelle,Vilim,Wilson
p. 441 - 443
(2007/11/03)
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