Aerobic Oxidation of Thiols to Disulfides Catalyzed by Diaryl Tellurides under Photosensitized Conditions

Photo-induced thiol coupling and C–H activation using nanocrystalline lead-halide perovskite catalysts

Cesium lead halide perovskite nanocrystals have been the first time utilized as photocatalysts for organic bond formations.

Simple low cost porphyrinic photosensitizers for large scale chemoselective oxidation of sulfides to sulfoxides under green conditions: targeted protonation of porphyrins

Large scale chemoselective photooxidation of sulfides to sulfoxides in the presence of the diacids ofmeso-tetra(phenyl)porphyrin with different acids is reported.

Base-controlled Fe(Pc)-catalyzed aerobic oxidation of thiols for the synthesis of S–S and S–P(O) bonds

Base-controlled Fe(Pc)-catalyzed S–S/S–P(O) bond formation.

Thermal conversion of primary alcohols to disulfidesviaxanthate intermediates: an extension to the Chugaev elimination

Heating primaryO-alkylS-difluoro(ethoxycarbonyl)methyl xanthates yields disulfides. This extends to the Chugaev elimination.

Phosphine-Free Synthesis of Metal Chalcogenide Quantum Dots by Directly Dissolving Chalcogen Dioxides in Alkylthiol as the Precursor

Semiconductor quantum dots (QDs) are competitive emitting materials in developing new-generation light-emitting diodes (LEDs) with high color rendering and broad color gamut. However, the use of highly toxic alkylphosphines cannot be fully avoided in the synthesis of metal selenide and telluride QDs because they are requisite reducing agents and solvents for preparing chalcogen precursors. In this work, we demonstrate the phosphine-free preparation of selenium (Se) and tellurium (Te) precursors by directly dissolving chalcogen dioxides in the alkylthiol under the mild condition. The chalcogen dioxides are reduced to elemental chalcogen clusters, while the alkylthiol is oxidized to disulfides. The chalcogen clusters further combine with the disulfides, generating dispersible chalcogen precursors. The resulting chalcogen precursors are suitable for synthesizing various metal chalcogenide QDs, including CdSe, CdTe, Cu₂Te, Ag₂Te, PbTe, HgTe, and so forth. In addition, the precursors are of high reactivity, which permits a shorter QD synthesis process at lower temperature. Owing to the high quantum yield (QYs) and easy tunability of the photoluminescence (PL), the as-synthesized QDs are further employed as down-conversion materials to fabricate monochrome and white LEDs.

Cs2 CO3 -Catalyzed Aerobic Oxidative Cross-Dehydrogenative Coupling of Thiols with Phosphonates and Arenes

An efficient Cs₂ CO₃ -catalyzed oxidative coupling of thiols with phosphonates and arenes that uses molecular oxygen as the oxidant is described. These reactions provide not only a novel alkali metal salt catalyzed aerobic oxidation, but also an efficient approach to thiophosphates and sulfenylarenes, which are ubiquitously found in pharmaceuticals and pesticides. The reaction proceeds under simple and mild reaction conditions, tolerates a wide range of functional groups, and is applicable to the late-stage synthesis and modification of bioactive molecules.

Batch and Flow Synthesis of Disulfides by Visible-Light-Induced TiO2 Photocatalysis

A mild and practical method for the preparation of disulfides through visible-light-induced photocatalytic aerobic oxidation of thiols has been developed. The method involves the use of TiO2 as a heterogeneous photocatalyst. The catalyst's high stability and recyclability makes this method highly practical. The reaction can be substantially accelerated in a continuous-flow packed-bed reactor, which enables a safe and reliable scale-up of the reaction conditions. The batch and flow protocol described herein can be applied to a diverse set of thiol substrates for the preparation of homo- and hetero-dimerized disulfides. Furthermore, biocompatible reaction conditions (i.e., room temperature, visible light, neutral buffer solution, and no additional base) have been developed, which permits the rapid and chemoselective modification of densely functionalized peptide substrates without recourse to complex purification steps.

Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4

The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyl)disulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2-4) or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6). We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted.

Deep Eutectic Mixture Catalysed the Synthesis of Disulfides Using Bunte Salts as Thiol Surrogates

Bunte salts, easily prepared from odourless sodium thiosulfates and various alkyl and aryl halides, acted as thiol surrogates for preparation of disulfides in the presence of hydrogen peroxide and a Brønsted-acidic deep eutectic mixture. The reaction proceeded smoothly to give the corresponding disulfide products in moderate to good yields, leaving odourless sodium bisulfite and water as the by-products. Moreover, this catalytic system could be readily recovered and reused several times without significant loss in activity.

Disulfide-based metal-free α-sulfanylation of ketones

An eco-friendly methodology for the direct α-sulfanylation of ketones has been developed by using diaryl disulfides as sulfanyl source affording ketosulfides in good to excellent yields and high selectivity.

Vis/NIR light driven mild and clean synthesis of disulfides in the presence of Cu2(OH)PO4 under aerobic conditions

A highly efficient one-pot strategy has been developed for the synthesis of disulfide in the presence of air under the irradiation of Vis/NIR light.

Serendipitous discovery of an efficient method for the synthesis of dimeric-RGD analogues using DMAP-photoirradiation

We describe a novel disulfide reaction via UV/DMAP methodology for efficient construction of simple disulfides and structurally complex peptides.

Reactivity of [U(CH2SiMe2NSiMe3)(NR2)2] (R = SiMe3) with elemental chalcogens: towards a better understanding of chalcogen atom transfer in the actinides

Addition of elemental chalcogens to [U(CH₂SiMe₂NSiMe₃)(NR₂)₂] results in formation of [U(ECH₂SiMe₂NSiMe₃)(NR₂)₂] (R = SiMe₃; E = S, Se, Te) via chalcogen insertion into the U–C bond.

Cubic Ag2O nanoparticle incorporated mesoporous silica with large bottle-neck like mesopores for the aerobic oxidative synthesis of disulfide

Ag₂O nanoparticle supported on silica with large bottle-neck like mesopores for the aerobic oxidative synthesis of disulphides in water.

Simple Conversion of Thiols to Disulfides in EtOH under Ambient Aerobic Conditions without using any Catalyst or Additive

EtOH was found to be an excellent medium for the aerobic S–S coupling reactions of various alkyl and aryl thiols. A series of useful disulfides RSSR have been synthesised in good to excellent yields without using any additional catalyst, oxidant or additive. Moreover, most products could be obtained by simply removing the solvent after completion of the reaction. Satisfactory results were obtained for both mg- and g-scale reactions.

Flavin-catalyzed aerobic oxidation of sulfides and thiols with formic acid/triethylamine

An efficient and practical method for flavin-catalyzed aerobic oxidation of sulfides and thiols with formic acid/TEA is described.

Amino acid and water-driven tunable green protocol to access S–S/C–S bonds via aerobic oxidative coupling and hydrothiolation

Arginine in conjunction with water has been employed as an effective and recyclable organocatalyst for oxidative coupling of thiophenols and hydrothiolation of alkynes.