Efficient preparation of unsymmetrical disulfides by nickel-catalyzed reductive coupling strategy

Regioselective 1,4-/1,3-Difunctionalization of 1,3-Enynes with Selenosulfonates in Water

1,4-/1,3-Regioselective bifunctionalization of 1,3-enynes with selenosulfonates in water under catalyst-free conditions for the construction of sulfonyl allene and 1,3-disulfonyl-conjugated dienes respectively have been developed. The reactions feature mild reaction conditions in aqueous solution and remarkable regioselectivity controlled by substrates.

Synthesis of (Furyl)Methyl Disulfides via Tandem Reaction of Conjugated Ene-Yne-Ketones with Acetyl-Masked Disulfide Nucleophiles

In this study, we outline a general method for the construction of various (furyl)methyl disulfides from acetyl-masked disulfide nucleophiles and ene-yne-ketones. This protocol is feathered by metal-free, simple experimental conditions, high efficiency, and scalable potential, which make it attractive and practical.

Copper-Catalyzed Chemoselective Coupling of N-Dithiophthalimides and Alkyl Halides: Synthesis of Unsymmetrical Disulfides and Sulfides

In this paper, we report an unprecedented copper-catalyzed disulfides or sulfides coupling reaction involving unactivated alkyl halides and N-dithiophthalimides. This reaction can be conducted under mild conditions using low-cost metal catalysts and exhibits high chemical selectivity and functional group compatibility, enabling the efficient assembly of various sulfides and disulfides.

Visible Light-Catalyzed Reactions of Polysulfide (DBSPS) with Aryldiazonium

A visible light-catalyzed radical coupling reaction of polysulfide reagents with aryldiazonium was developed, which gave thiosulfonates under mild conditions. In this reaction, the thiosulfonates were isolated in good yields with a broad tolerance to functional groups. And the synthesis of diaryl monosulfides were achieved through a step-by-step reaction of two molecular aryldiazonium with DBSPS, where the sulfur source was provided by DBSPS. It was worth noting that the reaction of this monosulfides could also be achieved by a one pot two-step process. The described polysulfide reagents were able to produce three new radicals: sulfonyl radicals, sulfur-sulfonyl radicals and sulfur-sulfur-sulfonyl radicals.

Ligand Relay for Nickel-Catalyzed Decarbonylative Alkylation of Aroyl Chlorides

Transition metal-catalyzed direct decarboxylative transformations of aromatic carboxylic acids usually require high temperatures, which limit the substrate's scope, especially for late-stage applications. The development of the selective decarbonylative of carboxylic acid derivatives, especially the most fundamental aroyl chlorides, with stable and cheap electrophiles under mild conditions is highly desirable and meaningful, but remains challenging. Herein, a strategy of nickel-catalyzed decarbonylative alkylation of aroyl chlorides via phosphine/nitrogen ligand relay is reported. The simple phosphine ligand is found essential for the decarbonylation step, while the nitrogen ligand promotes the cross-electrophile coupling. Such a ligand relay system can effectively and orderly carry out the catalytic process at room temperature, utilizing easily available aroyl chlorides as an aryl electrophile for reductive alkylation. This discovery provides a new strategy for direct decarbonylative coupling, features operationally simple, mild conditions, and excellent functional group tolerance. The mild approach is applied to the late-stage methylation of various pharmaceuticals. Extensive experiments are carried out to provide insights into the reaction pathway and support the ligand relay process.

Nickel-Catalyzed Reductive Arylation of α-Bromo Sulfoxide

A nickel-catalyzed cross-electrophile coupling of aryl iodides with α-bromo sulfoxide to access a diverse array of aryl benzyl sulfoxides has been discovered. These reactions occurred under mild conditions with excellent functional group tolerance so that optically enriched sulfoxides could be coupled with aryl iodides, generating corresponding sulfoxides with excellent stereochemical integrity. Furthermore, the scalability of this transformation was demonstrated. Initial mechanistic studies revealed that the reaction undergoes a radical pathway.

Simultaneous Preparation of Sulfides/Selenides and Sulfones via Synergistic Nickel-Catalyzed Reductive Coupling and SN2 Reaction

Sulfone compounds and thioether compounds are two highly valuable classes of compounds, but it is challenging to prepare sulfone and thioether compounds simultaneously and efficiently. Here we report that sulfides/selenides and sulfones can be obtained simultaneously using allyl bromide/benzyl bromide-activated alkyl bromides and thiosulfonates/selenosulfonates using a nickel-catalyzed reductive coupling and SN2 synergistic strategy, which is characterized by excellent atom and step economy, mild reaction conditions, broad functional group compatibility, and excellent yields.

Construction of β-Acetoxy or β-Hydroxyl Disulfides via Highly Regioselective Ring-Opening of Epoxides with Acetyl Masked Disulfide Nucleophiles

In the organic or water phase, acetyl masked disulfide nucleophiles were used as the disulfide source to react with a wide range of epoxides, affording various β-acetoxy or β-hydroxyl disulfides in good yields with high regioselectivity. This method features transition-metal-free, simple experimental conditions, high atom economy, and scalable potential, which make it attractive and practical.

Manganese-promoted reductive cross-coupling of disulfides with dialkyl carbonates

Manganese is a cheap and environmentally friendly metal on Earth. Herein, we report a manganese-promoted reductive cross-coupling using easily available and odorless disulfides as thiolating agents in an excellent 100% sulfur atom economy. The protocol featured a broad substrate scope, including various alkyl disulfides and excellent functional group compatibility, constructing diverse thioethers under simple conditions. Ultimately, thioethers can be prepared in gram-scale reactions and further transformed into structurally complex molecules.

Nickel-Catalyzed Acid Chlorides with Tetrasulfides for the Synthesis of Thioesters and Acyl Disulfides

Herein, we report a novel method for the synthesis of thioesters and acyl disulfides via nickel-catalyzed reductive cross-electrophile coupling of acid chlorides with tetrasulfides. This approach for the synthesis of thioesters and acyl disulfides is convenient and practical under mild reaction conditions, relying on easy availability. In addition, a wide range of thioesters and acyl disulfides were obtained in medium to good yields with good functional group tolerance. Moreover, thioesters and acyl disulfides can also be prepared at the gram scale, indicating that they have certain potential for industrial application.

High-entropy oxides as photocatalysts for organic conversion

A strategy involving organic photocatalytic conversion using hydrothermal synthesis of high-entropy oxide (HEO) (CoCuZnMnNa)Ox nanoparticles was developed. Under mild conditions, HEO nanoparticles were driven by visible light to achieve ideal yields and selectivity in sulfide oxidative coupling reactions and benzimidazole cyclization reactions, with a wide substrate range. This study is expected to contribute to the use of high-entropy oxides in organic photocatalysis.

PPh3/I2 Promoted Synthesis of Unsymmetrical Disulfides from Sodium Sulfites and 2-Mercaptobenzo Heterocyclics

A simple and efficient method for the synthesis of unsymmetrical disulfides is reported. Using sodium sulfites and 2-mercaptobenzo heterocyclic compounds as starting materials, the unsymmetrical sulfur-sulfur bonds could be quickly constructed in the PPh3/I2 reaction system under transition-metal-free conditions. This protocol has the advantages of mild reaction conditions, easily available starting materials, and wide substrate scope, showing potential synthetic value for the synthesis of a diversity of biologically or pharmaceutically active compounds.

Seed free synthesis of polyethylene glycol stabilized gold nanoprisms exploiting manganese metal at low pH

Manganese powder with a suitable potential (, -1.19 V) has never been investigated for the reduction of Au³⁺ (, 1.00 V). In this study, we have utilized and low pH dependent for the polyethylene glycol stabilized gold nanoprism synthesis by reducing AuCl^-₄ in the presence of thiol terminated polyethylene glycol as the stabilizing agent. The synthetic methodology for gold nanoprisms has been optimized by pH and Cl^- ion combination. Time dependent absorbance studies have been conducted to demonstrate the role of various reaction parameters such as the stabilizing agent, HCl concentration, temperature, and Mn metal. The synthesized gold nanoprism has been further utilized as a seed for nucleic acid and selected amino acid mediated edge and surface growth, respectively.

Nonbasic Synthesis of Thioethers via Nickel-Catalyzed Reductive Thiolation Utilizing NBS-Like N-Thioimides as Electrophilic Sulfur Donors

The nonbasic synthesis of unsymmetrical thioethers via nickel-catalyzed reductive thiolation between aryl(hetero) iodides and N-thioimides is illustrated. N-Bromosuccinimide (NBS)-like N-thioimides were found quite reactive toward thiolation with carbon electrophiles, and a series of structurally varied thioethers were successfully prepared under mild reaction conditions. The transformation was featured with the new application of the NBS-like reagents, good functional group tolerance, and late-stage modification of biologically active scaffolds, thus providing an expeditious and efficient platform to construct polyfunctional thioethers.

Practical synthesis of unsymmetrical disulfides promoted by bromodimethylsulfonium bromide

Oxidative cross-coupling of two thiols is the most direct tool for the synthesis of unsymmetrical disulfides and highly desirable across academia and industry. However, the inevitable formation of significant amounts of the corresponding symmetrical by-products is a major issue. We herein present a method toward the synthesis of unsymmetrical disulfides in which the homo-coupling of the thiols is effectively inhibited by adding the two thiols sequentially, taking advantage of rapid oxidation of the thiol by bromodimethylsulfonium bromide.

Electrochemical radical-mediated selective C(sp3)-S bond activation

Selective C(sp³)-S bond breaking and transformation remains a particularly important, yet challenging goal in synthetic chemistry. Over the past few decades, transition metal-catalyzed cross-coupling reactions through the cleavage of C(sp³)-S bonds provided a powerful platform for the construction of target molecules. In contrast, the selective activation of widespread C(sp³)-S bonds is rarely studied and remains underdeveloped, even under relatively harsh conditions. Herein, a radical-mediated electrochemical strategy capable of selectively activating C(sp³)-S bonds is disclosed, offering an unprecedented method for the synthesis of valuable disulfides from widespread thioethers. Importantly, compared with conventional transition-metal catalyzed C-S bond breaking protocols, this method features mild, catalyst- and oxidant-free reaction conditions, as well excellent chemoselectivity towards C(sp³)-S bonds. Preliminary mechanistic studies reveal that sulfur radical species are involved in the reaction pathway and play an essential role in controlling the site-selectivity.

Synthesis of N-acyl sulfenamides via copper catalysis and their use as S-sulfenylating reagents of thiols

Sulfur-heteroatom bonds such as S-S and S-N are found in a variety of natural products and often play important roles in biological processes. Despite their widespread applications, the synthesis of sulfenamides, which feature S-N bonds that may be cleaved under mild conditions, remains underdeveloped. Here, we report a method for synthesis of N-acyl sulfenamides via copper-catalyzed nitrene-mediated S-amidation reaction of thiols with dioxazolones. This method is efficient, convenient, and broadly applicable. Moreover, the resulting N-acetyl sulfenamides are highly effective S-sulfenylation reagents for the synthesis of unsymmetrical disulfides under mild conditions. The S-sulfenylation protocol enables facile access to sterically demanding disulfides that are difficult to synthesize by other means.

Dipotassium 1,3,4-thiadiazole-2,5-bis(thiolate) as a new S-donor for direct synthesis of symmetrical disulfides

In this research, a simple, efficient and novel protocol is eveloped for the direct synthesis of symmetrical disulfides using dipotassium 1,3,4-thiadiazole-2,5-bis(thiolate) as a new, low toxicity, inexpensive, stable solid and free of foul-smelling thiols for synthesize symmetric diaryl/dialkyl disulfides from aryl and alkyl halides in presence of MOF-199 and CuO nanoparticles. Significantly, using this method results in obtaining a variety of symmetrical disulfides in moderate to excellent yields (up to 98%).

Homocouplings of Sodium Arenesulfinates: Selective Access to Symmetric Diaryl Sulfides and Diaryl Disulfides

Symmetrical diaryl sulfides and diaryl disulfides have been efficiently and selectively constructed via the homocoupling of sodium arenesulfinates. The selectivity of products relied on the different reaction systems: symmetrical diaryl sulfides were predominately obtained under the Pd(OAc)2 catalysis, whereas symmetrical diaryl sulfides were exclusively yielded in the presence of the reductive Fe/HCl system.

Ni-catalyzed C-S bond construction and cleavage

Sulfur-containing compounds have attracted considerable interest due to their wide-ranging applications in pharmaceuticals, agriculture, natural products, and organic materials. The development of efficient and rapid methods for the construction and transformation of sulfur-containing compounds is of great importance. Since nickel is inexpensive and has a variety of valence states, strong nucleophilicity and low energy barriers for oxidative addition, the construction and transformation of sulfur-containing compounds by nickel-catalyzed cross-coupling have become important strategies. In addition, sulfur-containing compounds have also been playing increasingly important roles in the field of cross-coupling due to their thermodynamically stable but dynamic activity. This review will focus on nickel-catalyzed construction and transformation of various sulfide-containing compounds, such as sulfides, disulfides, and hypervalent sulfur-containing compounds.

Nickel(ii)/TPMPP catalyzed reductive coupling of oxalates and tetrasulfides: synthesis of unsymmetric disulfides

A Ni(ii)/TPMPP-catalyzed reductive cross-coupling reaction of benzyl oxalates and tetrasulfides to synthesize unsymmetric disulfides is reported.