Direct Thiolation Research Articles

Hypervalent Sulfur Derivatives as Sulfenylating Reagents: Visible-Light-Mediated Direct Thiolation of Activated C(sp2)-H Bonds with Dihalosulfuranes.

In contrast to hypervalent iodine compounds, the chemistry of their sulfur analogues has been considerably less explored. Herein, we report the direct C-H bond thiolation of electron-rich heterocycles, arenes, and 1,3-dicarbonyls by dichlorosulfuranes under mild conditions. Mechanistic studies and density functional theory calculations suggest the radical chain mechanism of the disclosed transformation. The key to success is attributed to a strikingly low S-Cl bond dissociation energy, which enables the generation of radical species upon exposure to daylight.

Photocatalytic synthesis of fluorescent and polarity-sensitive β-thiolated diketones for LDs-specific imaging

Fluorophores with easily tunable photophysical properties are highly desirable for bio-imaging. Herein, we develop a photocatalytic method for direct thiolation of β-diketone compounds with Rose Bengal as the photocatalyst under white light irradiation. The β-thiolated diketone compounds show a polarity-sensitive fluorescence emission and can be used for lipid droplets (LDs)-specific imaging with a high signal-to-noise ratio. We believe this photocatalytic method for direct preparation of fluorescent and polarity-sensitive β-thiolated diketones is promising for bioimaging applications.

Ag/K2S2O8‐Mediated Direct Thiolation and Selenylation of Carbazoles

AbstractThe first direct and selective 3,6‐di‐thiolation and 3,6‐di‐selenylation of carbazoles using diaryl disulfides/diselenide as the sulfur/selenium source were demonstrated. This simple, general, and efficient method could deliver a wide range of 3,6‐di‐sulfenyl‐carbazoles and 3,6‐di‐selenyl‐carbazoles from readily available starting materials with high regioselectivity in an easily‐operated one‐step reaction via a Ag/K2S2O8‐mediated protocol.

Direct Thiolation of the C(sp3)−H Bond Adjacent to Heteroatoms with Thiols under Alkaline Conditions

AbstractHerein, an operationally facile method for the construction of C−S bond through direct functionalization of C (sp3)−H bond adja‐cent to heteroatoms with thiols has been developed under weakly alkaline conditions. This methodology provides a convenient and efficient strategy to synthesize various aryl thioethers using a cheap and common solvent and base in moderate to good yields. The mechanistic studies indicate that a radical process is possibly involved and the sulfur radical (RS⋅) may be a reactive species during the transformations.

Visible-light-promoted C(sp3)–H thiolation of aliphatic ethers with thiosulfonates

Visible-light-promoted organic-dye-catalyzed synthesis of α-arylthioethers through direct thiolation of α-C(sp3)–H in aliphatic ethers with thiosulfonates at room temperature.

Metal-free direct thiolation of terminal alkynes with methyl sulfoxides

A metal-free method has been developed for the direct thiolation of terminal alkynes with methyl sulfoxides, which affords various alkynyl sulfides. This transformation features excellent functional group tolerance, good stability in large-scale preparation and atom economy, which makes this reaction a practical method for the synthesis of alkynyl sulfides.

Nickel-Catalyzed Regioselective Thiolation of Anilides with Thiols

AbstractAn efficient method for direct thiolation of anilides with thiols using NiCl2·6H2O as the catalyst is developed. Using this method, the desired products were successfully synthesized in moderate to good yields. Initial mechanistic studies suggest that this reaction proceeds through a radical pathway.

Metal-Free Direct Thiolation of Terminal Alkynes with Methyl Sulfoxides

Metal-Free Direct Thiolation of Terminal Alkynes with Methyl Sulfoxides

Aerobic Cross-Dehydrogenative Coupling Reactions for Selective Mono- and Dithiolation of Phenols.

A highly efficient strategy for the direct thiolation of phenols under transition metal-free and solvent-free conditions has been developed. These reactions are operationally simple with employing air (molecular oxygen) as an ideal oxidant and can selectively provide mono- and dithiolation products in good to excellent yields under basic conditions. The reaction tolerates a broad range of aryl thiols and arenes and is especially applicable for large-scale synthesis.

The organocatalytic synthesis of perfluorophenylsulfides via the thiolation of trimethyl(perfluorophenyl)silanes and thiosulfonates.

The organic superbase t-Bu-P4-catalyzed direct thiolation of trimethyl(perfluorophenyl)silanes and thiosulfonates was developed. Yields of perfluorophenylsulfides of up to 97% under catalysis of 5 mol% t-Bu-P4 were achieved. This method was shown to provide an efficient way to construct the perfluorophenyl-sulfur bond under mild metal-free reaction conditions.

Visible-light-promoted synthesis of secondary and tertiary thiocarbamates from thiosulfonates and N-substituted formamides.

A general visible-light-promoted metal-free synthesis of secondary and tertiary thiocarbamates starting from thiosulfonates and N-substituted formamides is developed. By employing rhodamine B as a photocatalyst and tert-butyl hydroperoxide (TBHP) as an oxidant, a wide scope of thiocarbamates can be obtained through direct thiolation of acyl C-H bonds under irradiation of blue light at room temperature for 12 h.

Iodine-promoted direct thiolation (selenylation) of imidazole with disulfides (diselenide): A convenient and metal-free protocol for the synthesis of 2-arylthio(seleno)imidazole

A convenient and metal-free protocol for the synthesis of 2-arylthio(seleno)imidazoles from imidazoles and disulfides (diselenides) was developed through the direct thiolation (selenylation) of imidazoles promoted by 0.5 equiv. of iodine. This process is scalable and tolerates a wide spectrum of disulfides (diselenides) to deliver products in high yields. Compared with previous methods, this protocol has the advantages of a simple operation, wide functional group tolerance and good yields, providing an efficient route to 2-arylthio(seleno)imidazoles, which are key structural scaffolds of many natural products.

Metal- and solvent-free direct C–H thiolation of aromatic compounds with sulfonyl chlorides

A simple method for the direct thiolation of aromatic compounds using sulfonyl chlorides was developed under metal- and solvent-free conditions.

Iodine/persulfate-promoted site-selective direct thiolation of quinolones and uracils

A simple and general method for direct thiolation of 4-quinolones with disulfides or thiols under I2/K2S2O8 system has been developed. Under the optimal conditions, the C–S bond coupling can take place effectively with good to decent yields and excellent regioselectivity of the S-linked products. The established metal-free site-selective approach was also applicable to transform a range of uracil substrates to the thio-substituted products under mild conditions. Further transformation to the sulfone derivatives can be conveniently performed in one-pot. These easy-to-handle protocols represent a useful and interesting synthetic alternative with good substrate scope and functional group compatibility.

Brønsted Base-Switched Selective Mono- and Dithiolation of Benzamides via Copper Catalysis.

A versatile protocol for the direct thiolation of an inert sp2 C-H bond is presented via a catalytic amount of copper catalysis, by switching related Brønsted bases and regulating the reaction time, and the corresponding mono- and dithiolation products can be obtained selectively in moderate to good yields. The reaction exhibits a relatively broad substrate scope and a good functional group tolerance, even with different heterocyclic amides and alkyl thiols.

Metal-free direct regioselective thiolation of imidazoheterocycles in water at room temperature

A metal-free direct thiolation of imidazoheterocycles with various thiophenol in water at room temperature has been developed. In addition, the chemistry provides several advantages including mild condition, high yields, good functional group tolerance, green solvents and suitable for large-scale operations.

Base‐Promoted Oxidative C(sp3)–S Bond Cross‐Coupling of Inactive Fluorenes and Thiols for the Synthesis of 9‐Monothiolated Fluorenes

The highly efficient and selective C(sp3)–S bond cross‐coupling method for the synthesis of 9‐thiolated fluorenes through a direct thiolation at 9‐C(sp3)–H of fluorenes with thiols is described. This reaction occurs at ambient conditions and shows good tolerance of functional groups including arylthiols and alkylthiols. A wide range of products is obtained in moderate to good yields. Besides, the reaction of benzothiophenol and fluorine generates unexpected 9‐benzylidene‐9H‐fluorene by eliminating hydrogen sulfide.

Metal-free regioselective direct thiolation of 2-pyridones.

A highly regioselective metal-free direct C-H thiolation of 2-pyridones with disulfides or thiols has been developed. A combination of persulfate and a commercially available halide source such as LiCl, NCS or I2 enables the successful direct incorporation of a sulfide moiety into the 5-position of pyridone under mild conditions, providing a useful and convenient approach for the preparation of a diverse array of 5-thio-substituted pyridones in moderate to excellent yields.

Copper-mediated direct thiolation of aryl C-H bonds with disulfides.

An efficient copper-mediated ortho-C(sp2)-H thiolation of aromatic amides directed by a novel directing group [4-chloro-2-(1H-pyrazol-1-yl)phenyl]amine has been developed without the need of other additives or oxidants, allowing for an increased usefulness. With the high compatibility of sterically demanding substrates, this reaction is scalable and can tolerate a wide scope of functional groups to provide alkyl and aryl thioethers in good to excellent yields (up to 93%). Furthermore, the protocol has been successfully implemented for the selenylation as well.

パラジウムまたはニッケル触媒による芳香族炭素-水素結合の直截硫黄化およびセレノ化反応

パラジウムまたはニッケル触媒による芳香族炭素-水素結合の直截硫黄化およびセレノ化反応