Sulfonate Research Articles

Mechanistic studies on single-electron transfer in frustrated Lewis pairs and its application to main-group chemistry.

Advances in the field of frustrated Lewis pair (FLP) chemistry have led to the discovery of radical pairs, obtained by a single-electron transfer (SET) from the Lewis base to the Lewis acid. Radical pairs are intriguing for their potential to enable cooperative activation of challenging substrates (e.g., CH4, N2) in a homolytic fashion, as well as the exploration of novel radical reactions. In this review, we will cover the two known mechanisms of SET in FLPs-thermal and photoinduced-along with methods (i.e., CV, DFT, UV-vis) to predict the mechanism and to characterise the involved electron donors and acceptors. Furthermore, the available techniques (i.e., EPR, UV-vis, transient absorption spectroscopy) for studying the corresponding radical pairs will be discussed. Initially, two model systems (PMes3/CPh3+ and PMes3/B(C6F5)3) will be reviewed to highlight the difference between a thermal and a photoinduced SET mechanism. Additionally, three cases are analysed to provide further tools and insights into characterizing electron donors and acceptors, and the associated radical pairs. Firstly, a thermal SET process between LiHMDS and [TEMPO][BF4] is discussed. Next, the influence of Lewis acid complexation on the electron acceptor will be highlighted to facilitate a SET between (pBrPh)3N and TCNQ. Finally, an analysis of sulfonium salts as electron acceptors will demonstrate how to manage systems with rapidly decomposing radical species. This framework equips the reader with an expanded array of tools for both predicting and characterizing SET events within FLP chemistry, thereby enabling its extension and application to the broader domain of main-group (photo)redox chemistry.

Divergent synthesis of nitrocyclopropanes and isoxazoline N-oxides from nitro compounds and vinyl sulfonium salts

A divergent approach toward polysubstituted nitro cyclopropanes and isoxazoline N-oxides is controlled by the choice of base and solvent.

Base mediated aza-[2 + 1] annulation and regioselective aziridine ring-opening cascade: mild synthesis of functionalized β-amino ketones from cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts.

Cyclic N-sulfonyl aldimines are well-known aza-[2C]-synthons for various [2 + n] annulation reactions. Herein we describe a novel base mediated [2 + 1] annulation and a regioselective aziridine ring-opening reaction cascade, which provides an efficient and distinct synthetic strategy from readily available cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts leading to β-amino ketone derivatives through the corresponding fused tri-substituted aziridines. This one-pot, two-step process involves formation of C-C and C-N bonds and subsequent cleavage of a C-N bond. The features of the developed reaction include the use of mild reaction conditions, broad substrate scope, and excellent yields. The synthetic utility of this approach was demonstrated by gram-scale operation and further product derivatizations.

Synthesis of alkynyl cyclopropa[c]coumarins via propargyl sulfonium salts as C1 synthons.

Herein, we present a novel approach for the preparation of alkynyl cyclopropa[c]coumarin derivatives with medium to good yields utilizing propargyl sulfonium salts as C1 synthons. Compared with Br-, using ClO4- as the counter anion significantly enhances the yield due to its lesser nucleophilic ability. This method features mild reaction conditions and a broad substrate scope with good diastereoselectivity when the substituted R1 group is at the 5-position of the coumarin scaffold.

Visible light/copper catalysis enabled Heck-like coupling between alkenes and cyclic sulfonium salts via selective C–S bond cleavage

A Heck-like coupling of cyclic sulfonium salts with alkenes via selective C–S bond cleavage using a copper complex as a photosensitizer through a visible-light-driven redox-neutral process has been developed.

Synthesis of alkynyl sulfides via base-promoted nucleophilic ring-opening of α-bromostyrene sulfonium salt.

An efficient method for the synthesis of alkynyl sulfides via a C(sp3)-S bond cleavage of α-bromostyrene sulfonium salts has been developed. This base-promoted nucleophilic ring-opening pathway allows the preparation of diverse alkynyl sulfide compounds using tetramethylene sulfoxide as the sulfur source. The reaction proceeds with good functional group tolerance and could be applied to the late-stage functionalization of bioactive molecules and drugs. Furthermore, the synthetic utility of this method was demonstrated by a one-pot synthesis, scale-up reaction and further modification of various alkynyl sulfide products.

Chalcogen bonding enabled photosynthesis of aryl selenides from aryl sulfonium salts

An efficient chalcogen bonding (ChB)-enabled photoactive charge transfer complex protocol for the synthesis of aryl–aryl/aryl–alkyl chalcogenides with aryl sulfonium salts is established.

Synthesis of S-alkyl phosphorothioates/phosphorodithioates via ring-opening reaction of sulfonium salts with S8, H-phosphonates or P4S10, and alcohols

A simple and practical method for the synthesis of S-alkyl phosphorothioates/phosphorodithioates through the three-component reaction of cyclic sulfonium salts with S8, H-phosphonates, or P4S10, and alcohols was readily developed.

Ball milling-promoting difunctionalization of alkynyl sulfonium salts with sulfinic acids towards (Z)-1,2-disulfonylethenes

A simple ball milling-mediated disulfonylation of alkynyl sulfonium salts with sulfinic acids for the stereoselective synthesis of various (Z)-1,2-disulfonylethenes has been developed under catalyst-, additive- and solvent-free conditions.

General electron–donor–acceptor complex mediated thioesterification reaction via site-selective C–H functionalization using aryl sulfonium Salts

We herein describe a versatile electron–donor–acceptor (EDA) mediated thioesterification reaction using aryl sulfonium salt (acceptor) with potassium thioacid salts (donor) under visible light irradiation.

Controllable tertiary amine-promoted photoactivation metal-free carbonylation of aryl sulfonium salts to aryl carboxylic acid derivatives

This paper describes a new method for the activation of aryl radicals via EDA complexes without metals and photosensitizers for carbonylation with various nucleophilic reagents under visible light.

Transition-metal-free glycosyl sulfonation of diaryliodonium salts with sodium glycosyl sulfinate: an efficient approach to access glycosyl aryl sulfones

Transition-metal-free glycosyl sulfonation employing a readily prepared sodium glycosyl sulfinate in conjunction with diaryliodonium salts was reported, featuring wide tolerance with unprotected sugar substrates.

Functionalized graphene-based materials for cementitious applications.

Graphene-based materials (GBM) are promising cementitious composite additives that can significantly improve the mechanical characteristics and durability of concrete due to their unique properties, such as high surface area and aspect ratio and excellent tensile strength, to name a few. To display their full potential, GBM have to be homogeneously dispersed into the aqueous environment of cement-based matrices. The present study addresses the issue of limited dispersibility in the aqueous media of GBM through the chemical functionalization of mono- and few-layer graphene structures with hydrophilic aryl sulfonate groups and shows that a series of mortar samples containing modified GBM exhibit increased flexural and compressive strength by up to 17% and 30%, respectively, compared to mortar references without additives.

Correction: Transition-metal-free glycosyl sulfonation of diaryliodonium salts with sodium glycosyl sulfinate: an efficient approach to access glycosyl aryl sulfones

Correction for ‘Transition-metal-free glycosyl sulfonation of diaryliodonium salts with sodium glycosyl sulfinate: an efficient approach to access glycosyl aryl sulfones’ by Jiaxin Luo et al., New J. Chem., 2024, 48, 4218–4223, https://doi.org/10.1039/D3NJ05942A.

Hypervalent iodide(iii)-mediated thiofluorination of alkenes and alkynes from thioureas/thiocarbamoyl fluorides with water and a nucleophilic fluoride source

This article discloses the unprecedented hypervalent iodide(iii)-mediated thiofluorination of alkenes/alkynes involving the cyclic sulfonium ion intermediate or traditional π-complexes.

β-Carbonyl sulfonium enables cysteine-specific bioconjugation for activity-based protein profiling in live cells.

Chemical labeling methods for proteins are highly researched. Herein, we introduced β-carbonyl sulfonium compounds for selective cysteine modification in proteins within biological systems. Structural tuning led to sulfonium-based probes with high reactivity and selectivity. These probes show excellent biocompatibility, cell uptake, and specificity towards cysteine profiling in live cells.

Single–atom Cu catalysts for the oxidative coupling of styrenes with aryl sulfones: from salts and zeolites to MOFs

Oxidative couplings in organic synthesis are typically performed with unrecoverable precious metal catalysts in solution. Here we show that CuCO3, Cu–supported zeolites and Cu–metal organic frameworks (MOFs) can replace AgNO3 as a catalyst for the oxidative coupling of styrenes with aryl sulfones, to give styrenyl sulfones. The single Cu atoms supported in zeolites show higher catalytic activity than the Cu salt as the basicity of the zeolite framework increases, to match the carbonate salt, and when embedded directly into a MOFs´ walls with oxamate ligands (thus with the proper electronic environment) they can be recycled for at least five times without any depletion in catalytic activity. These results showcase not only the substitution of a noble metal (Ag) by an abundant metal (Cu) in a metal–catalyzed oxidative coupling reaction, but also going from a salt to a supported solid catalyst, of high significance from a sustainable point of view.

Electron Donor-Acceptor Complex Enabled Radical Cyclization of α-Diazodifluoroethyl Sulfonium Salt with Unactivated Alkynes.

An α-diazodifluoroethane sulfonium reagent was developed in this study to undergo [3 + 2] radical cyclization with unactivated alkynes to give the corresponding 3-difluoromethyl pyrazoles under blue light irradiation conditions. The key to the success of this transformation lies in the formation of an electron donor-acceptor (EDA) complex between an electron-deficient α-diazo sulfonium salt and an electron-rich triaryl amine. This study circumvents a major substrate scope limitation in polar cycloaddition reactions of existent diazodifluoroethane reagents.

Diastereoselective Synthesis of Pyrroloquinolines via N-H Functionalization of Indoles with Vinyl Sulfonium Salts.

A [2 + 4]/[1 + 2] annulation approach was successfully established to construct pyrroloquinoline-fused cyclopropane in a highly diastereoselective fashion (>20:1 dr). The tetracyclic 1,7-fused indoles were efficiently obtained from readily available starting materials under mild conditions. This methodology displays impressive substrate generality with two reaction components. The products resulting from this doubly annulative strategy are useful synthetic intermediates.

An AIE fluorescent supramolecular polymer constructed by host-guest interactions among pillar[5]arenes/sulfonium salts for Pd2+ detection

An AIE fluorescent supramolecular polymer was fabricated on the interplay of pillar[5]arenes and sulfonium salts, manifesting substantially heightened fluorescence emissions. The linear supramolecular polymer exhibited significant fluorescence quenching with the addition of competitive molecules. Furthermore, the 1,2,3-triazole groups bestowed the supramolecular polymer with the valuable capability of detecting Pd2+ ions.