Sulfenyl Bromide Research Articles

A Method for the Synthesis of Thioindoles through Copper-Catalyzed C-S Bond Coupling Reaction.

We herein report the copper-catalyzed C-S bond coupling reaction of indoles with N-thiosuccinimides, resulting in moderate to excellent yields of mono- and bis-sulfenylated compounds such as arylthioindoles, alkylthioindoles, selenylated indoles, and cysteine-substituted indoles. Thioarylation and thioglycosylation at the C2 position of indole alkaloids in the Radix Isatidis were achieved via structural modification. The first total syntheses of isatindigotindolosides III and IV have been successfully carried out. The electrophilic sulfenyl bromides generated in situ can play an important role in the catalytic cycle.

α-Thiosubstituted boron difluoride dibenzoylmethanates

Treatment of tetraketone, in which two dibenzoylmethane groups are connected by a disulfide bridge through central (α) carbon atoms, gave a dinuclear complex containing boronodibenzoylmethanate fragments. Like an aromatic disulfide, this compound is cleaved by the action of sulfuryl chloride and bromine to form sulfenyl chloride or sulfenyl bromide derivatives. It was shown that these compounds enter into substitution and addition reactions common for sulfenyl halides, making it possible to obtain boronodibenzoylmethanate complexes containing various functional groups linked to the chelate cycle through the central carbon atom. Based on the results of studying the UV spectra of the obtained compounds, an assumption was made about the nature of the interaction of α and β substituents with the chelate ring.

Antibacterial Investigation and Structural Study on Few ortho-Mercapto-azo Compounds by Spectroscopic Techniques and DFT Calculation

An efficient method has been applied for the synthesis of bivalent ortho-mercapto-azo compounds by using green reduction, condensation using ionic liquid and green debenzylation. These greener steps provide the benefits like higher yields, shorter reaction times and simple work-up. Density functional theory (DFT) calculation and XRD analysis proved the ionic nature of these compounds as 2-arylbenzo-1-thia-2,3-diazol-2-ium (BTD+) bromide due to intramolecular cyclization between electrophilic sulfur atom and ortho-azo group. Some extent of LUMO orbital is present in electrophilic sulfur atom in BTD+ bromides. These sulfenyl bromides were also found to be active against antibacterial strains.

A quantum chemical study of the gas-phase homolytic S–Br bond dissociation enthalpies of sulfenyl bromides

Abstract This study reports the gas-phase homolytic S–Br bond dissociation enthalpies (at 298 K) for a set of 44 sulfenyl bromide derivatives (RSBr) obtained using the high-level G4 thermochemical protocol. For the species in this set, we find that the BDEs range from 178.0 kJ mol–1 (F3CSSBr) to 239.5 kJ mol–1 (HC(=NH)SBr). We have additionally reported molecule and radical stabilization enthalpies for all species, allowing for insights to be gained as to the effect of substituents in both the sulfenyl bromide reactants and the sulfur-centered radical products. In addition, we have also reported the BDEs of six sufinyl bromides (RS(=O)Br) and six sulfonyl bromides (RSO2Br). For the sulfinyl bromides, the BDEs range from 156.6 kJ mol–1 (F3CS(=O)Br) to 173.8 kJ mol–1 (tBuS(=O)Br), whilst for the sulfonyl bromides, the BDEs range from 211.0 kJ mol–1 (F3CSO2Br) to 226.2 kJ mol–1 (FSO2Br).

Sequential Interaction of Enamine with O, O-Dialkyldithiophosphoric Acid and Electrophilic Reagent

The adduct of O, O-dialkyldithiophosphoric acid and enamine reacts exothermically with an electrophilic reagent. In the case of sulfenyl bromide, the iminium salt reduced at the C-Br bond and bis(dialkoxythiophosphorylthio)-disulfide have been formed, experimentally evidencing the reaction of 2-halogenated ald- and ketimines with dithioic acid via the intermediate formation of enamine.

N‐Bromosuccinimide Promoted Direct Thiolation of Imidazoheteroaryl C‐H bonds with Disulfides

AbstractA one‐pot protocol has been demonstrated for the regioselective sulfenylation of imidazoheterocycles with disulfides. In this method, thiols are converted to sulfenyl bromides and reacted with 2‐phenylimidazo [1, 2‐a] pyridines. This simple procedure is highly capable for sulfenylation with readily available starting materials in good to excellent yields under transition metal and base free conditions.

ChemInform Abstract: Carbon Tetrabromide Mediated Oxidative Cyclocondensation of Ketones and Thioureas: An Easy Access to 2‐Aminothiazoles.

AbstractThe title reaction involves the generation of a sulfenyl bromide as an Umpolung intermediate of nucleophilic sulfur thus allowing the formation of the C—S bond.

Carbon tetrabromide mediated oxidative cyclocondensation of ketones and thioureas: an easy access to 2-aminothiazoles

A simple, mild, and efficient one-pot method for the synthesis of substituted 2-aminothiazoles has been reported. The reaction involves the formation of sulfenyl bromide as an umpolung intermediate of nucleophilic sulfur, which is responsible for C–S bond formation leading to oxidative cyclization of ketones and thioureas to furnish the desired products. Carbon tetrabromide was used as a convenient and mild brominating reagent under basic condition at room temperature to give 2-aminothiazoles in good to excellent yields.

Metal free sulfenylation of active methylene compounds and indole: TBATB mediated synthesis

The present work addresses a development of metal free one pot direct method for sulfenylation of active methylene compounds and indole. The reaction might proceed through sulfenyl bromide as an intermediate, which initiates the C–S bond formation. The reaction was performed using tetrabutylammonium tribromide (TBATB) as a brominating agent, CH2Cl2 as a solvent at room temperature.

A study of silver (I) perchlorate as an effective promoter for chemical glycosylation with thioimidates and thioglycosides

A study of silver (I) perchlorate as an effective promoter for chemical glycosylation with thioimidates and thioglycosides Scott J Hasty, Sneha C Ranade, Alexei V Demchenko Department of Chemistry and Biochemistry, University of Missouri–St Louis, St Louis, Missouri, USA Abstract: It has been previously acknowledged that perchlorate salts may be beneficial for the formation of 1,2-cis glycosides. Here, we demonstrate the effectiveness of silver (I) perchlorate as a powerful promoter of glycosyl thioimidate activation. Improved 1,2-cis selectivity was obtained, compared against that obtained with other silver (I) salts, including commonly-used triflate. The use of a combination of silver (I) perchlorate and methyl sulfenyl bromide to activate thioglycosides was also investigated. The cooperative use of these activation protocols was applied to a one-pot, two-step sequential activation, using thioimidate and thioglycoside building blocks. Keywords: carbohydrates, glycosylation, perchlorate, methodology, promoter

ChemInform Abstract: One‐Pot Oxidation of Alanine and Its Ethyl Ester with a Mild Oxidant 4′‐Methylazobenzene‐2‐sulfenyl Bromide.

AbstractOne pot oxidation of alanine (I) and its ethyl ester (V) with sulfenyl bromide (II) followed by hydrolysis leads ethanal (IV) and pyruvic acid (VII), resp., which are isolated as 2,4‐dinitrophenylhydrazones (no yields given).

Boron difluoride acetylacetonate sulfenyl(selenyl) halides

By cleavage of disulfide and diselenide derivatives of the boron difluoride acetylacetonate the previously unknown sulfenyl(selenyl) chlorides and bromides were prepared. It was shown that these compounds could be involved into the substitution and addition reactions characteristic of sulfenyl(selenyl) halides.

Allene-Substituted-1,3,2-Dioxaphospholanes in the Reactions with Sulfenyl Bromides and Selenenyl Bromides

The reactivity of allene-substituted-1,3,2-dioxaphospholanes towards sulfenyl bromides and selenenyl bromides has been investigated, and 2,5-dihydro-1,2-oxaphosphole derivatives have been obtained.

Carbon Tetrabromide Promoted Reaction of Amines with Carbon Disulfide: Facile and Efficient Synthesis of Thioureas and Thiuram Disulfides

A novel carbon tetrabromide promoted one-pot reaction of amines and carbon disulfide under mild conditions has been developed, which provides a straightforward and efficient access to thioureas and thiuram disufides, depending on the nature of the amines employed. The promotion effect is explained as the transient formation of a sulfenyl bromide intermediate from dithiocarbamate and carbon tetrabromide during the reaction.

Recent Developments in Disulfide Bond Formation

This review summarizes the recent developments of di-sulfidebond formation with a variety of reagents. The scope and limitationsof the presented methods are discussed. The syntheses of unsymmetricaldisulfides are highlighted in order to present the most versatileachievements. 1 Introduction 2 Preparation of Disulfides 2.1 By Oxidation of Thiols 2.2 By Reductive Coupling of Sulfonyl Chlorides 2.3 By Reaction with Sulfur Monochloride 2.4 By Radical Cyclization of Substituted Aminothiourea Derivatives- 2.5 Using 1-Chlorobenzotriazole 2.6 From Elemental Sulfur 2.7 From Organophosphorus Sulfenyl Bromide 2.8 From N-Trifluoroacetyl Arenesulfenamides 2.9 Using Phase-Transfer Catalysis 2.10 From a Thiol-Disulfide Exchange Reaction 2.11 From Thiocyanates 2.12 From 2-(Trimethylsilyl)ethyl Sulfides 2.13 From Thiosulfonates and Thiosulfates 2.14 From Thioesters 2.15 By Disulfide Exchange Reactions 2.16 From Tetrathiomolybdate 2.17 By Miscellaneous Reactions 3 Conclusions

Carbon Tetrabromide-Mediated Carbon−Sulfur Bond Formation via a Sulfenyl Bromide Intermediate

In the presence of carbon tetrabromide, a variety of dithiocarbamates, xanthates, dithioesters, and thioethers were prepared in one pot by reacting the corresponding dithioic acids or thiols with active methylene compounds/indole derivatives under mild conditions. The formation of a sulfenyl bromide intermediate is proposed as the key step, which initiates the C-S bond formation.

The Organophosphorus Sulfenyl Bromides as Versatile Reagents for Cysteine Derivatives Functionalization by Unsymmetrical Disulfide Bond Formation

We have developed a convenient method for the synthesis of L-cysteine unsymmetrical disulfides under mild conditions with good to excellent yields. Described method is based on the straightforward preparation of the organophosphorus sulfenyl bromide readily available from bis-(5,5-dimethyl-2-thiono-1,3,2-dioxaphosphorinanyl) disulfide. The unsymmetrical disulfides can be obtained for L-cysteine derivatives and thiols bearing neutral or acidic functionalities.

Versatile and Efficient Synthesis of ω-Functionalized Asymmetric Disulfides via Sulfenyl Bromide Adducts

Various types of asymmetric disulfides can be synthesized under mild conditions and in excellent yields by a method involving dialkoxylthiophosphoranesulfenyl halide precursors. This straightforward, rapid procedure is used to prepare a series of disulfides bearing neutral, acidic, and basic terminal groups as well as groups commonly used in biospecific self-assembled monolayers.

Formation of a Stable Sulfenic Acid by Hydrolysis of a Thionitrate and a Sulfenyl Bromide.

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Formation of a Stable Sulfenic Acid by Hydrolysis of a Thionitrate and a Sulfenyl Bromide

Abstract Alkaline hydrolysis of a thionitrate and a sulfenyl bromide bearing a bowl-type steric protection group produced a stable sulfenic acid. This provides a conclusive demonstration of these elementary processes. It was shown that a very efficient steric protection group is necessary to prevent the condensation of the sulfenate anion generated during the hydrolysis.