Bunte Salts Research Articles

Easy Access to α-Ketothioamides via Oxidative Amidation of Bunte Salts Using Electrolysis or Hypervalent Iodine.

Two new protocols leveraging electrochemical and hypervalent iodine-mediated synthesis of α-ketothioamides have been developed by using easily accessible and cost-effective Bunte salts and secondary amines. The methods are efficient, simple, and straightforward, and showcase the formation of C-N bonds across diverse substrates under ambient conditions.

Bunte Salts for Electrochemical Deuteroalkylthiolation of Heteroarenes

This study presents a strategy for the electrochemical deuteroalkylthiolation of heteroarenes, using Bunte salt as a deuterium‐alkylthio source. This reaction occurs in an undivided cell without the need for catalysts, oxidants, or electrolytes, yielding a variety of deuteroalkylthiolated heteroarenes.

Aminothiolation of alkenes with azoles and Bunte salts.

We have developed an intermolecular aminothiolation of simple olefins using Bunte salt as a thiolating agent. This protocol produces thiyl free radicals under PIDA oxidation conditions, eliminating the need for transition-metal catalysts. The method has a wide range of substrate applicability and is suitable for large-scale preparation and late-stage modification of drug molecules.

Electro-oxidative coupling of Bunte salts with aryldiazonium tetrafluoroborates: a benign access to unsymmetrical sulfoxides.

An electrochemical strategy for the synthesis of unsymmetrical sulfoxides has been explored using Bunte salts and aryldiazonium tetrafluoroborates under constant current electrolysis at room temperature. In addition to being eco-safe and using mild conditions, the present protocol is free from the use of metal/oxidant, and is endowed with a broad substrate scope and good functional group tolerance.

Efficient Construction of Symmetrical Diaryl Sulfides via a Supported Pd Nanocatalyst-Catalyzed C-S Coupling Reaction

Aryl sulfides play an important role in pharmaceuticals, biologically active molecules and polymeric materials. Herein, a general and efficient protocol for Pd@COF-TB (a kind of Pd nanocatalyst supported by a covalent organic framework)/DIPEA-catalyzed one-pot synthesis of symmetrical diaryl sulfides through a C-S coupling reaction from aryl iodides and Na2S2O3 is developed. More importantly, the addition of N,N-diisopropylethylamine (DIPEA) can not only enhance the catalytic activity of a Pd@COF-TB nanocatalyst, but also effectively inhibit the formation of biphenyl byproducts, which are a product of Ullmann reaction. Besides, it has been confirmed that the aryl Bunte salts generated in situ from Na2S2O3 and aryl iodides are the sulfur sources involved in this C-S coupling reaction. With the strategy proposed in this work, a variety of symmetrical diaryl sulfides could be obtained in moderate to excellent yields with a high tolerance of various functional groups. Moreover, a possible mechanism of this Pd nanoparticle-catalyzed C-S coupling reaction is proposed based on the results of controlling experiments.

Visible-Light-Induced Photocatalytic Trifluoromethylation of Bunte Salts: Easy Access to Trifluoromethylthiolated Synthons.

A metal-free visible-light-induced trifluoromethylation of Bunte salts of α-bromoketones/alkyl bromide/benzyl bromides/functionalized allyl (Baylis-Hillman) bromides has been accomplished using Langlois' reagent in the presence of inexpensive eosin Y as a photocatalyst to form the privileged trifluoromethylthiolated synthons. The method is straightforward, operationally simple, and endowed with broad substrate scope and good functional group tolerance.

Quality evaluation of synthesized modafinil used as pharmaceutical material

Modafinil is a drug used in the treatment of narcolepsy, approved by the FDA in 1998. In previous studies, modafinil was easily synthesized through three stages, in the Bunte salt medium, the overall yield of 74,56 %. The quality of the modafinil was evaluated following USP 41. The results have shown that the synthesized modafinil satisfied quality requirements in pharmacopoeia.

New 3,1,2,4-benzothiaselenadiazines, related π-heterocycles including Herz cations, radicals and molecular complexes, and Bunte salts

3,1,2,4-Benzothiaselenadiazines, 1,3,2,4-benzodithiadiazines and 1,2,4,3,5-benzotrithiadiazepines are synthesized from Ar–NSN–SiMe3and chalcogen chlorides, and converted into Herz salts, radicals and molecular complexes, and S- and Se-Bunte salts.

One-Pot Synthesis of 2-R-Naphtho[2,3-b]thiophene-4,9-diones via Cyclization of 2-(R-Ethynyl)-1,4-naphthoquinones with Na2S2O3.

The concise and efficient one-pot synthesis of 2-R-naphtho[2,3-b]thiophene-4,9-diones from 2-bromo-1,4-naphthoquinone and alkynes has been developed. The reaction proceeds through the formation of 2-(R-ethynyl)-1,4-naphthoquinones, which undergo transformation with Na2S2O3 to 2-R-naphtho[2,3-b]thiophene-4,9-diones via C-H sulfuration, accompanied by the formation of the aromatic Bunte salt, followed by its air oxidation and 5-endo-dig cyclization. The protocol is characterized by simplicity, good tolerance for functional groups, relatively mild conditions, and commercially available starting compounds.

Preparation of glycosyl disulfides and sulfides via the formation of glycosyl Bunte salts as thiol surrogates

A convenient odourless reaction condition has been developed for the preparation of symmetrical glycosyl disulfide derivatives and aryl glycosyl disulfide derivatives from corresponding glycosyl iodides via in situ formation of glycosyl Bunte salts as thiol surrogates. The reaction has been further extended towards the preparation of glycosyl sulfides derivatives from corresponding Bunte salt in the presence of sodium sulphide. Most of the reactions were high yielding and suitable for scaling up.

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions.

We described herein a selective method to prepare α-organylthio esters and α-organylthio ketones by the reaction of β-keto esters with sodium S-benzyl sulfurothioate or sodium S-alkyl sulfurothioate (Bunte salts) under basic conditions in toluene as the solvent at 100 °C. When 4 equivalents of a base were used, a series of differently substituted α-thio esters were obtained with up to 90% yield. On the other hand, employing 2 equivalents of a base, α-thio ketones were achieved after 18 h under air. Furthermore, after a shorter reaction time, the isolation of keto–enol tautomers was possible, revealing them as significant intermediates for the mechanism elucidation.

Ag-Cu copromoted direct C2-H bond thiolation of azoles with Bunte salts as sulfur sources.

A direct C2-H thiolation of azoles with Bunte salts was achieved under the combined action of copper and silver salts. This protocol could furnish various substituted 2-thioazoles in moderate to good yields. This method has a broad substrate scope and shows good functional group tolerance.

Iodine-catalyzed thioallylation of indoles using Bunte salts prepared from Baylis-Hillman bromides.

Metal-free iodine-catalyzed regioselective thioallylation of indoles has been accomplished at room temperature using Bunte salts prepared from Baylis-Hillman bromides. The resulting multi-functional C3 thioallylated indoles exhibit ample structural diversity and good functional group tolerance.

Efficient generation of thiolate sugars from glycosyl Bunte salts and its application to S-glycoside synthesis

A one-pot aqueous solution method for synthesis of S-glycoside derivatives has been developed. Firstly, unprotected sugars were converted into glycosyl Bunte salts from which thiolate sugars can be generated efficiently using Na2S. The subsequent addition reaction with vinyl compounds or organic halides has successfully been demonstrated, giving rise to the corresponding S-glycosides.

Copper-Catalyzed Oxidative Thioamination of Maleimides with Amines and Bunte Salts.

Herein, we describe the first example of copper-catalyzed oxidative thioamination of maleimides with secondary amines and Bunte salts with the achievement of C-N and C-S bonds in a single flask. The protocol showcases a prominently broad substrate scope and is also efficient for the late-stage modification of an array of pharmaceuticals. Preliminary mechanistic investigation indicates copper-catalyzed oxidative amination of maleimides with amines to form reactive enaminone and subsequent intermolecular alkenyl C-H thiolation.

Bunte Salts and Congeners as Efficient Sulfur Surrogates: Recent Advances

Bunte Salts and Congeners as Efficient Sulfur Surrogates: Recent Advances

Transition metal-free α-Csp3-H oxidative sulfuration of benzyl thiosulfates with anilines to form N-aryl thioamides.

A metal-free approach to N-aryl thioamides from Bunte salts and anilines in DMSO has been developed. This method tolerated a wide range of functional groups on the aromatic ring, providing an ideal way to N-aryl thioamides in good to excellent yields from cheap and easily available starting materials. A plausible mechanism was also proposed based on the X-ray single crystal diffraction, NMR and MS analyses of DMSO-concerning intermediates.

Bunte Salt CH2FSSO3Na: An Efficient and Odorless Reagent for Monofluoromethylthiolation.

A practical and efficient monofluoromethylthiolation that employs the typical Bunte salt, sodium S-(fluoromethyl) sulfurothioate, as the sulfur source is described. This reagent reacts readily with a variety of aryl amines and aryl thiols. The high tolerance of functional groups demonstrates the potential of this reaction. In addition, this method is suitable for the late-stage monofluoromethylthiolation of complex bioactive molecules.

Synthesis of Thiophosphates by Coupling of Phosphates with Bunte Salts under Mild Conditions

A simple, green, and efficient method has been developed for the preparation of thiophosphates with sodium S-benzyl thiosulfates. The method uses an NaBr-catalyzed coupling reaction of Bunte salts with phosphonates in the presence of an acid and hydrogen peroxide (30%), and the desired products were obtained in good yields.

Synthesis of 3-Sulfenylindoles from Indoles and Various Sulfenylation Agents through Aerobic Oxidative C–S Bond Coupling

A novel aerobic catalytic oxidation system for the sulfenylation of indoles with a variety of sulfenylation agents through oxidative C–S bond coupling has been successfully developed. The reactions were performed with potassium iodide as the catalyst, sodium nitrite as the co-catalyst, and molecular oxygen as the terminal oxidant in the presence of acetic acid. Under the optimal reaction conditions, a number of indoles could be sulfenylated with Bunte salts, thiols, or disulfides to generate 3-sulfenylindoles in good yields. This protocol provided an efficient and environmentally benign strategy for the synthesis of 3-sulfenylindoles.