Synthesis of Functionalized Diaryl Sulfides by Cobalt-Catalyzed Coupling between Arylzinc Pivalates and Diaryl Disulfides

Copper-Catalyzed One-Pot Synthesis of N,N-4-Triphenylthiazol-2-amines

Herein, we reported an efficient copper-catalyzed strategy for the synthesis of N,N-4-triphenylthiazol-2-amines from bromoacetophenone, phenylthiourea and iodobenzene. This method features good functional group tolerance, easy availability of starting materials and simplicity of operation, which provides an alternative method for the synthesis of 2-aminothiazoles.

Visible-light induced decarboxylative coupling of phenoxyacetic acid with disulfides: synthesis of α-arylthioanisole derivatives

Photoredox-catalyzed cross-coupling reaction is an efficient strategy for the construction of organic molecules. Herein, we developed a method to synthesize α-arylthioanisoles by constructing C-S bonds in the presence of a Ru-photoredox catalyst. Thus, a series of α-arylthioanisole compounds were efficiently obtained through decarboxylative cross-coupling under mild conditions. This protocol features high efficiency, broad substrate scope and good functional group tolerance.

Samarium-Oxo/Hydroxy Cluster: A Solar Photocatalyst for Chemoselective Aerobic Oxidation of Thiols for Disulfide Synthesis

Oxidation contributes as a secondary driver of the prevailing carbon emission in the chemical industries. To address this issue, photocatalytic aerobic oxidation has emerged as a promising alternative. However, the challenge of achieving satisfactory chemoselectivity and effective use of solar light has hindered progress in this area. In this context, the present study introduces a novel homogeneous photocatalyst, [Sm6O(OH)8(H2O)24]I8(H2O)8 cluster (Sm-OC), via a unique auxiliary ligand-free oxidative hydrolysis. Using Sm-OC as catalyst, a solar photocatalyzed aerobic oxidation of thiols has been developed for the synthesis of valuable disulfides. Remarkably, this catalyst manifested a significant turnover number ≥2000 under tested conditions. Sm-OC-catalyzed aerobic oxidation showcased remarkable chemoselectivity. In thiol oxidations, despite the vulnerability of disulfides toward overoxidation, overoxidized byproducts or oxidation of nontarget functional groups was not detected across all 28 tested substrates. This investigation presents the first application of a lanthanide-oxo/hydroxy cluster in photocatalysis.

Selective Construction of C-S/S-N Bonds from N-Substituted O-Thiocarbamates and Indoles under Transition-Metal-Free Conditions

A method for the selective construction of S-N/C(sp2)-S bonds using N-substituted O-thiocarbamates and indoles as substrates is reported. This protocol features good atom utilization, mild conditions, short reaction time, and wide substrate scope, which can provide a convenient path for the functionalization of indoles. In addition, the reaction could be scaled up on gram scale, showing potential application value in industry synthesis.

Selective Synthesis of Sulfonamides and Sulfenamides from Sodium Sulfinates and Amines

An effective method was explored for the selective synthesis of sulfonamides and sulfenamides using sodium sulfinates and amines as starting materials. This method offers mild reaction conditions, a broad substrate scope, high efficiency, and readily accessible materials, making it suitable and an alternative strategy for the preparation of a variety of biologically or pharmaceutically active compounds.

Arylazo sulfones: multifaceted photochemical reagents and beyond

The photochemical action of arylazo sulfones under visible light irradiation has recently gained considerable attention for the construction of carbon-carbon and carbon-heteroatom bonds in organic synthesis. The inherent dyedauxiliary group (-N2SO2R) embedded in the reagent is responsible for the absorption of visible light even in the absence of a photocatalyst, additive or oxidant, leading to the generation of three different radicals, viz. aryl (carbon-centred), sulfonyl (sulphur-centred) and diazenyl (nitrogen-centred) radicals, under different reaction conditions. Encountering a reagent with such a versatile behaviour is quite rare, which makes arylazo sulfones a highly interesting class of compounds. The mild reaction conditions under which these reagents can operate are an added advantage. Recently, they are also being used as non-ionic photoacid generators (PAGs), electron acceptors, and hydrogen atom transfer (HAT) and imination reagents in a number of synthetic transformations. They have displayed substantial damaging effect on the structure of DNA in the presence of light which can lead to their use as phototoxic pharmaceuticals for cancer treatment. Moreover, their photochemistry is also being exploited in polymerization reactions (as photoinitiators) and in materials chemistry (surface modification).

Construction and characterization of a magnetic nanoparticle-supported Cu complex: a stable and active nanocatalyst for synthesis of heteroaryl-aryl and di-heteroaryl sulfides

Diaryl and di-heteroaryl sulfides exist in the structure of many drugs and important biological compounds, also these compounds are well-known in medicinal chemistry due to important biological and pharmaceutical activities. Therefore, the development of novel, ecofriendly and efficient catalytic systems for the preparation of diaryl and di-heteroaryl sulfides is a very attractive and important challenge in organic synthesis. In this attractive methodology, we wish to introduce Fe3O4-supported 3-amino-4-mercaptobenzoic acid copper complex (Fe3O4@AMBA-CuI) nanomaterials as a novel and efficient magnetically recoverable catalyst for the preparation of heteroaryl-aryl and di-heteroaryl sulfides with high yields through reaction of heteroaryl halides with aryl or heteroaryl boronic acids and S8 as the sulfur source under ecofriendly conditions. This catalytic system was very efficient and practical for a diverse range of heteroaryl substrates including benzothiazole, benzoxazole, benzimidazole, oxadiazole, benzofuran, and imidazo[1,2-a]pyridine, because the desired diaryl and di-heteroaryl sulfides were prepared with high yields. The reusability-experiments revealed that the Fe3O4@AMBA-CuI nanocatalyst can be magnetically separated and reused at least six times without a significant decrease in its catalytic activity. VSM and ICP-OES analyses confirmed that despite using the Fe3O4@AMBA-CuI nanocatalyst 6 times, the magnetic properties and stability of the catalyst were still maintained. Although all the obtained heteroaryl-aryl and di-heteroaryl sulfide products are known and previously reported, the synthesis of this number of heteroaryl-aryl and di-heteroaryl sulfides has never been reported by any previouse methods.

Mechanistic Study on Selenium- and Sulfur-Mediated Isomerization of Hydroxamic Acids

An in-depth computational study reveals the intriguing mechanism of the recently reported isomerization of hydroxamic acids into para-aminophenols catalyzed by phenylselenyl bromide under mild conditions. The computations not only align with the reported experimental data, effectively explaining observed phenomena such as para-selectivity but also shed light on crucial aspects of the reaction mechanism that establish limitations on the scope of the studied rearrangement. Additionally, a joint theoretical/experimental study was performed to examine the potency of the phenylsulfenyl bromide to mediate the reaction under the same conditions.

Glyoxylic Acid Monohydrate-Promoted Formation of the C-SO2 Bond Starting from Maleimides/Quinones and Sodium Sulfinates

By using glyoxylic acid monohydrate as a promoter, a wide range of substances containing a C-SO2 bond could be obtained from N-substituted maleimides or quinones and sodium sulfinates. The protocol features mild reaction conditions, short reaction time, and good atomic economics, which provides an alternative protocol for the α-sulfonylation of α,β-unsaturated ketones.

Catalytic Asymmetric Synthesis of Zinc Metallacycles

Transition-metal-catalyzed reductive coupling reactions of alkynes and imines are attractive methods for the synthesis of chiral allylic amines. Mechanistically, these reactions involve oxidative cyclization of the alkyne and the imine to generate a metallacyclic intermediate, which then reacts with H2 or a H2 surrogate to form the product. As an alternative to this hydrogenolysis pathway, here we show that transmetalation to zinc can occur, forming a zinc metallacycle product. This organozinc product serves as a versatile nucleophile for carbon-carbon and carbon-heteroatom coupling reactions. Mechanistic studies based on isotopic labeling experiments and DFT calculations suggest that the key transmetalation step occurs between a Co(II) species and ZnCl2.

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.

One-Pot Synthesis of Benzoxazole/Benzothiazole-Substituted Esters by Michael Addition: A Selective Construction of C-N/C-S Bonds

An efficient and convenient synthesis of benzoxazole/benzothiazole-substituted esters in a one-pot strategy is reported. In this investigation, a selective construction of C-N and C-S bonds via simple addition is performed. Thus, using substituted 2-aminophenols/2-aminobenzenethiols, TMTD (tetramethylthiuram disulfide) and α,β-unsaturated esters as starting substrates, C-N and C-S bonds can be selectively constructed by means of the Michael addition reaction. This protocol features high selectivity, high atomic economy, mild conditions, good functional tolerance and good to excellent yields, showing the potential value for the preparation of some biologically and pharmaceutically active compounds.

Selective C-S Bond Constructions Using Inorganic Sulfurs via Photoinduced Electron Donor-Acceptor Activation

By complementing traditional transition metal catalysis, photoinduced catalysis has emerged as a versatile and sustainable way to achieve carbon-heteroatom bond formation. This work discloses a visible-light-induced reaction for the formation of a C-S bond from aryl halides and inorganic sulfuration agents via electron donor-acceptor (EDA) complex photocatalysis. Divergent formations of organic sulfide and disulfide have been demonstrated under mild conditions. Preliminary mechanistic studies suggest that visible-light-induced intracomplex charge transfer within the monosulfide-anion-containing EDA complex permits the C-S bond construction reactivity.

One-Pot Synthesis of N,N-Diphenyl-2-benzothiazolamines from 1-(2-Iodophenyl)-3-phenylthioureas and Iodobenzenes

An efficient copper-catalyzed synthesis of a variety of N,N-diphenyl-2-benzothiazolamines was developed. Starting from substituted 1-(2-iodophenyl)-3-phenylthioureas and substituted iodobenzenes, the reaction proceeded smoothly via a tandem manner in the presence of CuI to afford the corresponding N,N-diphenyl-2-benzothiazolamine derivatives with good functional group tolerance. The protocol features simple performance, easily available starting materials, a one-pot manner, and good functional group tolerance, providing a practical strategy for the preparation of poly-functionalized amines.

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.

Synthesis of Unsymmetric Thiosulfonates Starting from N-Substituted O-Thiocarbamates: Easy Access to the S-SO2 Bond

Using phenyliodine diacetate as an oxidant and nickel acetate as a promoter, a wide range of unsymmetric thiosulfonates could be furnished easily in moderate to excellent yields starting from N-substituted O-thiocarbamates and sodium sulfinates. This protocol features mild conditions, short reaction times, and high atomic utilization, which can provide an alternative method for the synthesis of unsymmetric thiosulfonates. In addition, the reaction could be scaled up on a gram scale, showing potential application value in industry.

Easy S-Alkylation of Arylthioureas and 2-Mercaptobenzothiazoles Using Tetraalkylammonium Salts under Transition-Metal-Free Conditions

A highly-efficient and practical method for S-alkylation of arylthioureas was reported. Using tetraalkylammonium salts as alkylation reagents, a series of 68 S-substituted aryl-isothioureas were obtained in good to excellent yields under transition-metal-free conditions. The protocol features simple performance, broad functional group tolerance, good to excellent yields, and easily available starting materials, showing potential synthetic value for the preparation of diverse biologically or pharmaceutically active compounds.

Nickel-Catalyzed C-S Reductive Cross-Coupling of Alkyl Halides with Arylthiosilanes toward Alkyl Aryl Thioethers

A nickel-catalyzed C-S reductive cross-coupling of alkyl halides with arylthiosilanes for producing alkyl aryl thioethers is developed. This reaction is initiated by umpolung transformations of arylthiosilanes followed by C-S reductive cross-coupling with alkyl halides to manage an electrophilic alkyl group onto the electrophilic sulfur atom and then construct a C(sp³)-S bond, and features exquisite chemoselectivity, excellent tolerance of diverse functional groups, and wide applications for late-stage modification of biologically relevant molecules.

One-Pot Synthesis of Benzoazole-Substituted Thioenamines via a Cross Dehydrogenation Coupling (CDC) Reaction

An iodine-catalyzed synthesis of benzoazole-substituted thioenamines in a one-pot manner was reported. Using 2-aminothiophenols (or 2-aminophenols or 1,2-phenylenediamines), tetramethylthiuram disulfide (TMTD), and enamines (mainly indoles) as starting materials, the target C(sp²)-S formation products (benzoazole-substituted thioenamines) could be furnished smoothly in good yields. The reaction might proceed through an electrophilic substitution pathway in a cross dehydrogenation coupling (CDC) manner. The protocol is metal-free and features easy performance, a one-pot manner, a good functional group tolerance, and good yields.

Iodine promoted cyclization of N,N′-diphenylthiocarbamides with enaminones: a protocol for the synthesis of poly-substituted 2-iminothiazolines

An iodine promoted cyclization reaction between N,N′-diphenylthiocarbamides and enaminones was achieved, providing a series of poly-substituted 2-iminothiazolines.

Construction of Diverse C–S/C-Se Bonds via Nickel Catalyzed Reductive Coupling Employing Thiosulfonates and A Selennofonate Under Mild Conditions

A nickel-catalyzed reductive cross coupling between organic iodides and thiosulfonates and a selennofonate under mild conditions is disclosed. This pracitical method provides facile access to a series of unsymmetrical thioethers...

Thiolate-assisted copper(i) catalyzed C–S cross coupling of thiols with aryl iodides: scope, kinetics and mechanism

The scope and mechanism of the C–S cross coupling of thiophenols with aryl iodides using a Cu(i) catalyst in a ligand-free environment is disclosed.

The journey of C–S bond formation from metal catalysis to electrocatalysis

This perspective describes the journey of C–S bond constructions starting from transition metal catalysis through oxidant catalysis, photocatalysis and very recently employed electrocatalysis by using various sulfur surrogates.

Reaction of 3-Cl/OMe-Substituted 5-Nitrobenzisothiazoles with Hydrazine: Structural and Computational Evidence for Rearrangement Pathways Implicating Intramolecular Formation of Pivotal Meisenheimer Complexes

In projected structure-activity relationship studies of the novel diheteroarylamide-based anti-HIV agent 2 (1C8), one objective was to evaluate the influence of incorporating the central amide motif in 2 into a five-membered pyrazolone ring, as found in 3. It was envisaged that compound 3 could be prepared through reaction of 3-hydrazino-5-nitrobenzisothiazole 5 with the methyl ester of 4-chloropyridine-3-carboxylic acid, followed by N-methylation of the pyridine nitrogen. However, the reaction of 3-methoxyl-5-nitrobenzisothiazole with hydrazine resulted in formation of ring-opened hydrazonate product 18. In the corresponding reaction with 3-chloro-5-nitrobenzisothiazole, a different rearrangement product 19 was formed, in which two 2,1-benzisothiazole units are joined by a sulfur bridge. Meisenheimer complex formation, favored by the presence of the 5-nitro substituent on the benzisothiazole ring, was postulated to be a key feature in the formation of these deep-seated rearrangement products. Support for the proposed formation of the pivotal Meisenheimer complexes and their subsequent evolution to the observed products in which the benzisothiazole sulfur atom is either expelled or maintained in the isomeric 2,1-benzisothiazole system was obtained by density function theory calculations.

Copper-Catalyzed Cycloaddition of Heterobicyclic Alkenes with Diaryl Disulfides to Synthesize Dihydrobenzo[b]thiophene Derivatives

A novel copper-catalyzed cycloaddition of diaryl disulfides to heterobicyclic alkenes has been developed. The C-S and C-C bonds can be formed simultaneously on the C═C bond of the olefins via a single-step cycloaddition to afford a series of 2,3-dihydrobenzo[b]thiophene derivatives. This reaction exhibits excellent diastereoselectivity and relatively broad substrate scope. Various functional groups attached to the substrates are tolerated in this protocol to give the corresponding exo adducts in moderate yields.

Recent Progress in Utilization of Functionalized Organometallic Reagents in Cross Coupling Reactions and Nucleophilic Additions

Organometallic compounds have become increasingly important in organic synthesis because of their high chemoselectivity and excellent reactivity. Recently, a variety of organometallic reagents were found to facilitate transition-metal-catalyzed cross-coupling reactions and nucleophilic addition reactions. Here, we have summarized the latest progress in cross-coupling reactions and in nucleophilic addition reactions with functionalized organometallic reagents present to illustrate their application value. Due to the tremendous contribution made by the Knochel group towards the development of novel organometallic reagents, this review draws extensively from their work in this area in recent years.

Introduction

1 Transition-Metal-Catalyzed Cross Couplings Involving Organo­zinc Reagents

2 Transition-Metal-Catalyzed Cross Couplings Involving Organomagnesium Reagents

3 Transition-Metal-Free Cross Couplings Involving Zn and Mg ­Organometallic Reagents

4 Nucleophilic Additions Involving Zn and Mg Organometallic Reagents

5 Cross-Coupling Reactions or Nucleophilic Additions Involving Mn, Al-, La-, Li-, Sm- and In-Organometallics

6 Conclusion

Ligand-Free Copper(I)-Mediated Cross-Coupling Reactions of Organostannanes with Sulfur Electrophiles

The synthesis of aryl thioether through the cross-coupling of C-S bond is a highly attractive area of research due to the prevalence of aryl thioether in bioactive natural products, functional materials, agrochemicals, and pharmaceutically active compounds. Herein, we report a ligand-free Cu(I) mediated electrophilic thiolation of organostannanes with sulfur electrophiles. A selective transfer of alkyl groups was achieved in reactions with alkyl carbastannatranes affording congested thioethers. This study offers a unified method to access diaryl and aryl alkyl thioethers and was demonstrated in the context of late-stage modifications..

Lipshutz-type bis(amido)argentates for directed ortho argentation

Bis(amido)argentate (TMP)2Ag(CN)Li2 (3, TMP-Ag-ate; TMP = 2,2,6,6-tetramethylpiperidido) was designed as a tool for chemoselective aromatic functionalization via unprecedented directed ortho argentation (DoAg). X-Ray crystallographic analysis showed that 3 takes a structure analogous to that of the corresponding Lipshutz cuprate. DoAg with this TMP-Ag-ate afforded multifunctional aromatics in high yields in processes that exhibited high chemoselectivity and compatibility with a wide range of functional groups. These included organometallics- and transition metal-susceptible substituents such as methyl ester, aldehyde, vinyl, iodo, (trifluoromethanesulfonyl)oxy and nitro groups. The arylargentates displayed good reactivity with various electrophiles. Chalcogen (S, Se, and Te) installation and azo coupling reactions also proceeded efficiently.

A template free protocol for fabrication of a Ni(ii)-loaded magnetically separable nanoreactor scaffold for confined synthesis of unsymmetrical diaryl sulfides in water

In the present report, an environmentally benign magnetically recoverable nickel(ii)-based nanoreactor as a heterogeneous catalyst has been developed via a template free approach. The catalytic performance of the synthesized catalyst is assessed in the confined oxidative coupling of arenethiols with arylhydrazines to form unsymmetrical diaryl sulfides under aerobic conditions. The salient features of our protocol include oxidant- and ligand-free conditions, use of water as a green solvent, room temperature and formation of nitrogen and water as the only by-products. Moreover, a broad range of functional groups are tolerated well and provide the corresponding diaryl sulfides in moderate to good yields. Moreover, the heterogeneous nature of the catalyst permits facile magnetic recovery and reusability for up to seven runs, making the present protocol highly desirable from industrial and environmental standpoints.

An environmentally benign nickel(ii)-based magnetic nanoreactor has been developed for oxidative coupling of arenethiols with arylhydrazines to form unsymmetrical diaryl sulfides in water at room temperature.

Aryldithiocarbamates as thiol alternatives in Cu-catalyzed C(aryl)-S coupling reactions using aryldiazonium tetrafluoroborate salts

An efficient method for the synthesis of unsymmetrical diaryl sulfides has been developed by the C-S cross coupling of aryldithiocarbamates and aryldiazonium salts in the presence of CuI-2,2'-bipyridine and Zn. Aryldithiocarbamate compounds have been used here as thiol substitutes. The protocol shows wide substrate scope and good yields of the products.

Copper-Catalyzed Electrophilic Thiolation of Organozinc Halides by Using N-Thiophthalimides Leading to Polyfunctional Thioethers

(Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5-10 % Cu(OAc)₂ ⋅H₂ O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrophilic thiolation was extended to the introduction of trifluoromethylthio (SCF₃ ), thiocyanate (SCN), and selenophenyl (SePh) groups. The utility of this method was shown in a seven-step synthesis of a potent cathepsin D inhibitor in 34 % overall yield.