Sulfur Transfer Reagent Research Articles

Geminal-dithiol-based precursors for reactive sulfur species.

Caged gem-dithiols have been developed as the donors of reactive sulfur species (RSS), but the chemistry of free gem-dithiols as RSS donors has not been well understood. Herein, we report the study of a free gem-dithiol, 1,3-diphenylpropane-2,2-dithiol, as the precursor for several RSS. It releases H2S under physiological conditions and can be converted to a mono-S-nitrosothiol, which serves as a NO donor. Furthermore, it can be converted to 3,3-dibenzyldithiirane, which is an active sulfur transfer reagent and can induce S-persulfidation.

3,4-Dichloro-1,2,5-thiadiazole: a commercially available electrophilic sulfur transfer agent and safe resource of ethanedinitrile

3,4-Dichloro-1,2,5-thiadiazole is introduced as a safe and efficient sulfur transfer reagent. By applying this commercially available reagent, the symmetrical trisulfides and ethanedinitrile were simultaneously obtained by reacting various thiols with this reagent at room temperature. This reagent is non-toxic, inexpensive, and commercially available. In addition, no higher-order polysulfides were detected in all cases after the completion of the reaction. The short reaction times (20–50 min), excellent selectivity, and high yield of the trisulfides are some attractive merits of this reagent for the preparation of trisulfides. The reaction is one-pot, and isolation-purification of intermediates is not required. The procedure was readily scaled up to 5 grams. A mechanism is presented to explain the chemistry.

Mechanochemical Synthesis of Short DNA Fragments.

We demonstrate the first mechanochemical synthesis of DNA fragments by ball milling, enabling the synthesis of oligomers of controllable sequence and length using multi-step, one-pot reactions, without bulk solvent or the need to isolate intermediates. Mechanochemistry allowed for coupling of phosphoramidite monomers to the 5'-hydroxyl group of nucleosides, iodine/water oxidation of the resulting phosphite triester linkage, and removal of the 5'-dimethoxytrityl (DMTr) protecting group in situ in good yields (up to 60 % over three steps) to produce DNA dimers in a one-pot manner. H-Phosphonate chemistry under milling conditions enabled coupling and protection of the H-phosphonate linkage, as well as removal of the 5'-DMTr protecting group in situ, enabling a one-pot process with good yields (up to 65 % over three steps, or ca. 87 % per step). Sulfurization of the internucleotide linkage was possible using elemental sulfur (S8) or sulfur transfer reagents, yielding the target DNA phosphorothioate dimers in good yield (up to 80 % over two steps). This work opens the door to creation of solvent-free synthesis methodologies for DNA and RNA therapeutics.

Comparison of conventional and microwave-assisted synthesis of some new sulfenamides under free catalyst and ligand

Sulfenamide and its derivatives (S–N bond) have been synthesized with classical method in the literature. However, microwave-assisted synthesis of a series of N-(substituted phenylthio), N-(benzylthio), N-(cyclothio), and N-(2-mercaptobenzimidazolyl)amines has been not in the literature yet. They have been obtained from treating some amines (4 mmol) with thiophthalimides (PhthSR, 1 mmol) using sulfur transfer reagent in the presence of 2-ethoxyethanol (β-ee, neat) under microwave irradiation at 50 °C. The scope of this reaction was shown by the efficient synthesis of sulfenamides in good to excellent yields of 70–98% under free catalyst and ligand. Nine of the synthesized sulfenamide derivatives are novel. All of the thiols react with morpholine to give corresponding sulfenamides in excellent yields of 78–98%. Thiophenol, 4-methylthiophenol, 4-chlorothiophenol, and 4-fluorothiophenol react with cyclohexylamine to give corresponding sulfenamides in high yields 81–92%. Thiophenol, 4-methylthiophenol, 4-chlorothiophenol react with pyrrolidine to give corresponding sulfenamides in good yields of 70–76%. We observed that the reaction of t-butylamine with N-(phenylthio)phthalimide gave desired sulfenamide under microwave irradiation in the presence of DPPH as radical scavenger reagent in high yield of 93%. Aniline, benzylamine, 1-hexylamine, ethanolamine, diethylamine, N-ethyl-n-butylamine, N-ethylaniline, N-benzylmethylamine, t-butylamine react with thiols to give symmetrical disulfides instead of desired products under microwave irradiation, 2-ethoxyethanol as a solvent (neat), and at 50 °C. In this study, microwave-assisted synthesis method was compared with the classical method. All the products obtained were purified with chromatographic method and the analysis of these products was confirmed with IR, 1H NMR, 13C NMR spectroscopy, MS spectrometry, and elemental methods.

K₂S₂O₈-Promoted Aryl Thioamides Synthesis from Aryl Aldehydes Using Thiourea as the Sulfur Source.

Thiourea as a sulfur atom transfer reagent was applied for the synthesis of aryl thioamides through a three-component coupling reaction with aryl aldehydes and N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMAC). The reaction could tolerate various functional groups and gave moderate to good yields of desired products under the transition-metal-free condition.

CuI-catalyzed thioarylation of active methylene compounds with in situ generated benzenethiols: Preparation of α-thioaryl-β-dicarbonyls and 4-thioaryl-5-pyrazolones

In this paper, a one-step copper-catalyzed procedure for oxidative coupling of active methylene compounds including cyclic β-diketones, cyclic β-ketoesters and 5-pyrazolone with benzenethiols is described. Benzenethiols are in situ generated in the reaction mixture from aryl halides and thiourea as sulfur transfer reagent. α-Thioaryl compounds are obtained in excellent yields and in short reaction time via the process which is free from the foul smell of thiols.

Conversion of organic halides to disulfanes using KCN and CS2

A sulfur transfer reagent was produced in situ upon stirring a mixture of KCN and CS2 in DMF at r.t. for 15min, which after heating with an alkyl halide or aryl halide and CuI gave the corresponding symmetric dialkyl or diaryl disulfide, respectively, in high to excellent yields.

Synthesis of sulfides via reaction of aryl/alkyl halides with S8 as a sulfur-transfer reagent catalyzed by Fe3O4-magnetic-nanoparticles-supported L-Histidine-Ni(II)

ABSTRACTOne-pot synthesis of symmetrical diaryl/alkyl sulfides in high yields from the reaction between aryl/alkyl halides and S8 can be carried out in a short period, using Fe3O4@SiO2@His@Ni(II) as a reusable catalyst. The present approach offers the advantages of a clean reaction, simple methodology and high efficiency, and avoids the use of a toxic catalyst.

Simple and green method for synthesis of symmetrical dialkyl disulfides and trisulfides from alkyl halides in water; PMOxT as a sulfur donor

ABSTRACTAn environmentally new, mild and efficient method has been developed for the synthesis of dialkyl disulfides and dialkyl trisulfides in aqueous conditions by a reaction between alkyl halides (and tosylate) and potassium-5-methyl-1,3,4-oxadiazole-2-thiolate (PMOxT) as a sulfur transfer reagent. The advantages of this method are that it occurs under mild reaction conditions, it is base free, it uses water as the solvent and it occurs in high yields. A variety of dialkyl disulfides and dialkyl trisulfides can be obtained in good to excellent yields up to 98%.

Metal Organic Framework 199- Catalyzed Domino Sulfur-Coupling and Transfer Reactions: The Direct Synthesis of Symmetric Diaryl Disulfides from Aryl Halides

A highly porous metal–organic framework Cu3 BTC2 (copper(II)-benzene-1,3,5-tricarboxylate) that known as MOF-199 was synthesized, and characterized by common methods including, FT-IR, XRD, EDX, SEM and then used as an efficient and recyclable catalyst for the direct synthesis of symmetric organic disulfides. A variety of symmetric diaryl disulfides with high chemoselectivity can be obtained by domino reaction of aryl halides (and tosylates) and potassium 5-methyl-1,3,4-oxadiazole-2- thiolate, as the base and sulfur-transfer reagent, in the presence of MOF-199.

Catalyst-Free, Regioselective Ring Opening of Donor–Acceptor Cyclopropanes: Synthesis of Functionalized Mono- and Disulfides

Interesting sulfur compounds such as monosulfides, symmetrical disulfides, unsymmetrical disulfides, and other 1,3-bifunctionalized compounds were synthesized using benzyltriethylammonium tetrathiomolybdate, [BnNEt₃]₂MoS₄, as the sulfur transfer reagent via regioselective ring opening of donor–acceptor cyclopropanes without the addition of any catalyst.

ChemInform Abstract: Dithioates of Meldrum′s Acid, Dimedone, and Barbituric Acid, Novel Sulfur Transfer Reagents for the One‐Pot Copper‐Catalyzed Conversion of Aryl Iodides into Diaryl Disulfides.

AbstractThe best yields are obtained with dithioate of meldrum′s acid as sulfur transfer reagent to provide diaryl disulfides from aryl iodides.

Alternative Protocol for the Synthesis of Symmetrical Dibenzyl Diselenides and Disulfides

A one-pot protocol for the preparation of symmetrical dibenzyl diselenides and disulfides from the corresponding benzyl alcohols employing NaBH₂Se₃ and NaBH₂S₃ as selenium-transfer and sulfur-transfer reagent, respectively, is described. Structurally diverse substituted benzyl alcohols afforded the corresponding diselenides and disulfides in good to excellent yields. The protocol is simple and mild, and the products were obtained within a short reaction time.

Dithioates of Meldrum’s acid, dimedone, and barbituric acid, novel sulfur transfer reagents for the one-pot copper-catalyzed conversion of aryl iodides into diaryl disulfides

We report herein the first application of CH-acid dithioates as sulfur transfer reagents. A new route for the synthesis of diaryldisulfides using the copper-catalyzed conversion of aryl iodides in the presence of Melderum’s acid, dimedone or barbituric acid dithioates is discussed.

Synthesis of mixed glycosyl disulfides/selenenylsulfides using benzyltriethylammonium tetrathiomolybdate as a sulfur transfer reagent

An easy and mild method has been developed for the synthesis of mixed glycosyl disulfides/selenenylsulfides from glycosyl halides and diaryl/dialkyl dichalcogenides in the presence of benzyltriethylammonium tetrathiomolybdate [(BnEt3N)2MoS4]. The salient feature of this method is the sulfur transfer from [BnEt3N]2MoS4 to form glycosyl disulfides which with excess tetrathiomolybdate further undergo exchange reaction with other dichalcogenides in a one-pot operation.

ChemInform Abstract: An Efficient, One‐Pot and CuCl‐Catalyzed Route to the Synthesis of Symmetric Organic Disulfides via Domino Reactions of Thioacetamide and Aryl (Alkyl) Halides.

AbstractThe novel method employs thioacetamide as sulfur transfer reagent in the presence of KF‐Al2O3.

An efficient, one‐pot and CuCl‐catalyzed route to the synthesis of symmetric organic disulfides via domino reactions of thioacetamide and aryl (alkyl) halides

In this article, a simple, general and novel method for the synthesis of diaryl (dialkyl) disulfides from aryl (alkyl) halides is described. This is a convenient approach that involves the use of commercially available and inexpensive thioacetamide as a sulfur transfer reagent in the domino process for the synthesis of symmetric organic disulfides. Copyright © 2013 John Wiley & Sons, Ltd.

De novo synthesis of 1-deoxythiosugars

A short and efficient chemical synthesis of biologically potent and novel 1-deoxythiosugars is accomplished. Introduction of sulfur mediated by benzyltriethylammonium tetrathiomolybdate, as a sulfur transfer reagent through nucleophilic double displacement of tosylate in α,ω-di-O-tosyl aldonolactones in an intramolecular fashion is the key feature. The subsequent reduction of thiosugar lactones with borohydride exchange resin (BER) offers a number of deoxythiosugars in good overall yield.

ChemInform Abstract: A Novel Copper‐Catalyzed, One‐Pot Synthesis of Symmetric Organic Disulfides from Alkyl and Aryl Halides: Potassium 5‐Methyl‐1,3,4‐oxadiazole‐2‐thiolate as a Novel Sulfur Transfer Reagent.

AbstractVarious title compounds can be prepared in a simple manner.

A novel copper-catalyzed, one-pot synthesis of symmetric organic disulfides from alkyl and aryl halides: potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as a novel sulfur transfer reagent

A new method is reported for the synthesis of symmetric diaryl and dialkyl disulfides from aryl and alkyl halides in the presence of copper using potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as the base, ligand, and sulfur-transfer reagent.