Air Oxidative Coupling of Thiols to Disulfides Catalyzed by Fe(III)/NaI

Iranpoor, Nasser; Zeynizadeh, Behzad

doi:10.1055/s-1999-3693

Cited by 111 publications

(27 citation statements)

References 3 publications

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“…The ␣-mercaptophenylacetic acids 4a-b, d were obtained as a mixture with the corresponding disulfide derivatives 5a-b, d, whereas the nitro derivative 3c gave only undesired side products. The oxidation of the thiol groups by using catalytic ferric chloride and sodium iodide (47) led to pure (Ͼ95% by 1 H NMR analysis) disulfides 5a-b, d. The disulfide moiety is often a convenient protecting group, and thiols are easily obtained by the reduction of disulfides. Here, compounds 5a-b, d were reduced with sodium borohydride to give pure (Ͼ95% by 1 H NMR analysis) thiols 4a-b, d. The individual optical isomers, R-and S-thiomandelic acids (15a and 15b), were synthesized by the procedure of Strijtveen and Kellog (48).…”

Section: Methodsmentioning

confidence: 99%

Thiomandelic Acid, a Broad Spectrum Inhibitor of Zinc β-Lactamases

Mollard¹,

Moali²,

Papamicaël³

et al. 2001

Journal of Biological Chemistry

108

127

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Resistance to ␤-lactam antibiotics mediated by metallo-␤-lactamases is an increasingly worrying clinical problem. Candidate inhibitors include mercaptocarboxylic acids, and we report studies of a simple such compound, thiomandelic acid. A series of 35 analogues were synthesized and examined as metallo-␤-lactamase inhibitors. The K i values (Bacillus cereus enzyme) are 0.09 M for R-thiomandelic acid and 1.28 M for the Sisomer. Structure-activity relationships show that the thiol is essential for activity and the carboxylate increases potency; the affinity is greatest when these groups are close together. Thioesters of thiomandelic acid are substrates for the enzyme, liberating thiomandelic acid, suggesting a starting point for the design of "pro-drugs." Importantly, thiomandelic acid is a broad spectrum inhibitor of metallo-␤-lactamases, with a submicromolar K i value for all nine enzymes tested, except the Aeromonas hydrophila enzyme; such a wide spectrum of activity is unprecedented. The binding of thiomandelic acid to the B. cereus enzyme was studied by NMR; the results are consistent with the idea that the inhibitor thiol binds to both zinc ions, while its carboxylate binds to Arg 91 . Amide chemical shift perturbations for residues 30 -40 (the ␤ 3 -␤ 4 loop) suggest that this small inhibitor induces a movement of this loop of the kind seen for other larger inhibitors.The ␤-lactam antibiotics are among the most useful antibacterial chemotherapeutic agents, but their efficiency is being continuously challenged by the emergence of resistant strains of pathogenic bacteria. ␤-Lactamases, which inactivate these antibiotics by hydrolyzing their endocyclic amide bond, play a major role in this resistance (1). ␤-Lactamases have been divided into four classes on the basis of their amino acid sequences and catalytic mechanisms (2). The mechanisms of class A, C, and D enzymes, which contain a nucleophilic serine side chain as a key component of their active site, have been extensively studied, due to their established clinical importance. Class B enzymes are metalloproteins that require one or two zinc ion(s) for their activity (3). The first metallo-␤-lactamase (MBL) 1 to be discovered was produced by an innocuous strain of Bacillus cereus (4), but in the last 20 years, MBLmediated resistance has appeared in several pathogenic strains including Bacteroides fragilis, Aeromonas hydrophila, Stenotrophomonas maltophilia, and Serratia marcescens (5). Even more threatening is the rapid dissemination of some metallo-␤-lactamase genes by horizontal transfer, involving both plasmid-and integron-borne genetic elements. For instance, the IMP enzymes that were first isolated in clinical isolates of S. marcescens and Pseudomonas aeruginosa have also been found in Klebsiella, Alcalinogenes, Acinetobacter, and Shigella strains (6), and up to four variants of IMP-1 have been described so far (7-10).The MBLs with known sequences share a small number of conserved motifs, but otherwise they show significant sequence diversity and have th...

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Section: Methodsmentioning

confidence: 99%

Thiomandelic Acid, a Broad Spectrum Inhibitor of Zinc β-Lactamases

Mollard¹,

Moali²,

Papamicaël³

et al. 2001

Journal of Biological Chemistry

108

127

View full text Add to dashboard Cite

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“…The residue was then washed with CH 2 Cl 2 (2 Â 20 mL) and after filtration and removal of the solvent, the crude product crystallized from CH 2 Cl 2 : EtOH to give purified product (0.24 g, 1 mmol, 96%), which was identified by comparison with authentic dibenzyl disulfid using TLC spot, melting point (71 -738C; Lit. [17] 728C).…”

Section: Oxidation Of Benzyl Thiol Under Solvent-free Conditionsmentioning

confidence: 99%

Oxidation of Organic Compounds by Potassium Permanganate Supported on Montmorillonite K10

Shaabani

Bazgir

Lee

2004

Synthetic Communications

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The oxidation of organic compounds by potassium permanganate supported on Montmorillonite K10 has been studied under solvent-free conditions and the results compared with those from corresponding reactions where the reductants are dissolved in methylene chloride. Under both sets of conditions, primary benzylic and secondary alcohols are converted to aldehydes and ketones respectively, sulfides are oxidized to sulfones, and thiols undergo oxidative coupling to give disulfides.

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“…The palladium catalyst may also be involved in this oxidation step, because the heating of 17a in DMSO at 120°C in the absence of palladium resulted in the formation of disulfide 19a in only 11% yield. 62,63,[65][66][67] Disulfide 19 formed from the corresponding ethenethiol 17 may undergo oxidative addition to palladium, leading to complex 20. 68,69) Subsequent C-H cyclization can give rise to the desired benzo[b] thiophene 18.…”

Section: -46)mentioning

confidence: 99%

Synthesis of Heterocyclic Compounds through Palladium-Catalyzed C–H Cyclization Processes

Inamoto

2013

CHEMICAL & PHARMACEUTICAL BULLETIN

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Herein, we describe our development of synthetic methods for heterocyclic compounds based on the palladium-catalyzed carbon-hydrogen bond (C-H) functionalization/intramolecular carbon-heteroatom (nitrogen or sulfur) bond formation process. By this C-H cyclization method, we efficiently prepared various N-heterocycles, including indazoles, indoles, and 2-quinolinones, as well as S-heterocycles such as benzothiazoles and benzo[b]thiophenes. Yields are typically good to high and good functional-group tolerance is observed for each process, thereby indicating that the method provides a novel, highly applicable synthetic route to the abovementioned biologically important heterocyclic frameworks. As an application of this approach, an auto-tandem-type, one-pot process involving the oxidative Heck reaction and subsequent C-H cyclization using cinnamamides and arylboronic acids as starting materials in the presence of a palladium catalyst was also developed for the rapid construction of the 2-quinolinone nucleus.

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Air Oxidative Coupling of Thiols to Disulfides Catalyzed by Fe(III)/NaI

Abstract: A very simple and mild reaction is described for the efficient coupling of thiols at room temperature catalyzed by Fe (III)/ NaI in the presence of air.

Cited by 111 publications

References 3 publications

Thiomandelic Acid, a Broad Spectrum Inhibitor of Zinc β-Lactamases

Thiomandelic Acid, a Broad Spectrum Inhibitor of Zinc β-Lactamases

Oxidation of Organic Compounds by Potassium Permanganate Supported on Montmorillonite K10

Synthesis of Heterocyclic Compounds through Palladium-Catalyzed C–H Cyclization Processes

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