A Redox-neutral Nickel-catalysed Sulfonylation of (Hetero)aryl Boronic Acids with 2-Chlorothiazoles

A redox-neutral nickel-catalysed sulfonylation for arylsulfone synthesis was developed. (Hetero)aryl boronic acids reacted with potassium metabisulfite (K2 S2 O5 ) and readily available 2-chlorothiazoles in the presence of air-stable Ni(OTf)2 and 4,4-di-tert-butyl bipyridine (dtbpy) as a commercially available ligand to produce the corresponding 2-sulfonylthiazoles in moderate to excellent yields. This practical protocol tolerates a wide range of substrates including boronic acids and 2-chloro(benzo)thiazoles without additional bases, allowing the direct synthesis of functional arylsulfones.

Ni-Catalyzed Hydrosulfonylation of Alkenes with Aromatic Iodides and K2S2O5

Hydrosulfonylation of alkenes with readily available aromatic iodides via a SO2-insetion strategy is presented. The combination of non-noble Ni catalysis with (iPr)3SiH as the final reductant enables the efficient formation of aryl and heteroaryl sulfinate intermediates, which undergo Michael-type additions to electron-deficient alkenes for initiating the hydrosulfonylation process. Moreover, the superiority of this protocol is demonstrated by broad substrate scope and good functional group compatibility.

Metal-catalyzed C-S bond formation using sulfur surrogates

Sulfur-containing compounds are present in a wide range of biologically important natural products, drugs, catalysts, and ligands and they have wide applications in material chemistry. Transition metal-catalyzed C-S bond-forming reactions have successfully overcome the obstacles associated with traditional organosulfur compound syntheses such as stoichiometric use of metal-catalysts, catalyst-poisoning and harsh reaction conditions. One of the key demands in metal-catalyzed C-S bond-forming reactions is the use of an appropriate sulfur source due to its odor and availability. The unpleasant odor of many organic sulfur sources might be one of the reasons for the metal-catalyzed C-S bond-forming reactions being less explored compared to other metal-catalyzed C-heteroatom bond-forming reactions. Hence, employing an appropriate sulfur surrogate in the synthesis of organosulfur compounds in metal-catalyzed reactions is still of prime interest for chemists. This review explores the recent advances in C-S bond formation using transition metal-catalyzed cross-coupling reactions and C-H bond functionalization using diverse and commercially available sulfur surrogates. Based on the different transition metal-catalysts, this review has been divided into three major classes namely (1) palladium-catalyzed C-S bond formation, (2) copper-catalyzed C-S bond formation, and (3) other metal-catalyzed C-S bond formation. This review is further arranged based on the different sulfur surrogates. Also, this review provides an insight into the growing opportunities in the construction of complex organosulfur scaffolds covering natural product synthesis and functional materials.

The Same Oxidation-State Introduction of Hypervalent Sulfur via Transition-Metal Catalysis

Sulfonyl compounds have attracted considerable interest due to their extensive applications in drug discovery, agricultural, and material science. The access to the assembly of SO₂ -containing compounds via the same oxidative-state introduction of hypervalent sulfur has come to the fore in the recent years. Especially, the transition-metal-involved synthesis of hypervalent sulfur compounds is the most effective strategy since SO₂ is easy to insert into the metal-carbon bonds. This review discusses the application of the same oxidation-state introduction of hypervalent sulfur strategy under the transition-metal-catalyzed conditions, and presents according to different metal catalysts and the synthesized diversity hypervalent sulfur-containing compounds skeletons, including sulfonamides, sulfones, sulfinamides, sulfonyl acids and sulfonyl fluorides.

Synthesis of Sulfones via Ru(II)-Catalyzed Sulfination of Boronic Acids

Ruthenium(II) complexes catalyze the insertion of sulfur dioxide into (het)aryl and alkenyl boronic acids. The transmetalation-sulfination process proceeds with DABSO in the presence of 5 mol % RuCl₂(PPh₃)₃ in methanol at 100 °C. The intermediate sulfinate salt can be quenched with various electrophiles such as alkyl halides, epoxides, Michael acceptors, and λ³-iodanes in moderate to good yields. The reported sulfone synthesis can be performed either as a direct one-pot or one-pot two-step procedure depending on the reactivity of the electrophile.

Palladium-catalyzed three-component cascade arylthiolation with aryldiazonium salts as S-arylation sources

A novel palladium-catalyzed three-component cascade arylthiolation for the assembly of 3-sulfenylindoles and 3-sulfenylbenzofurans is described, with aryldiazonium salts as the ideal S-arylation sources.

Facile, regioselective oxidative selenocyanation of N-aryl enaminones under transition-metal-free conditions

The present selenocyanation is applied for the synthesis of selenocyanated chromones, indoles and anilines in good to excellent yields.

SO2 conversion to sulfones: development and mechanistic insights of a sulfonylative Hiyama cross-coupling

A Pd-catalyzed Hiyama cross-coupling reaction using SO2 is described. The use of silicon-based nucleophiles leads to the formation of allyl sulfones under mild conditions with a broad functional group tolerance. Control experiments coupled with DFT calculations shed light on the key steps of the reaction mechanism, revealing the crucial role of a transient sulfinate anion.

Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts

Organosulfur compounds have long played a vital role in organic chemistry and in the development of novel chemical structures and architectures. Prominent among these organosulfur compounds are those involving a sulfur(IV) center, which have been the subject of countless investigations over more than a hundred years. In addition to a long list of textbook sulfur-based reactions, there has been a sustained interest in the chemistry of organosulfur(IV) compounds in recent years. Of particular interest within organosulfur chemistry is the ease with which the synthetic chemist can effect a wide range of transformations through either bond formation or bond cleavage at sulfur. This review aims to cover the developments of the past decade in the chemistry of organic sulfur(IV) molecules and provide insight into both the wide range of reactions which critically rely on this versatile element and the diverse scaffolds that can thereby be synthesized.

Synthesis of β-Sulfonyl Amides through a Multicomponent Reaction with the Insertion of Sulfur Dioxide under Visible Light Irradiation

A multicomponent reaction of styrenes, aryldiazonium tetrafluoroborates, sulfur dioxide, nitriles, and water in the presence of a photocatalyst at room temperature is performed. This vicinal aminosulfonylation of styrenes with the insertion of sulfur dioxide under visible light irradiation proceeds efficiently with excellent chemoselectivity, giving rise to the corresponding β-sulfonyl amides in moderate to good yields.

Thiourea dioxide as a source of sulfonyl groups: photoredox generation of sulfones and sulfonamides from heteroaryl/aryl halides

Thiourea dioxide as the source of sulfonyl groups for the efficient synthesis of heteroaryl sulfones and sulfonamides from heteroaryl halides under visible light irradiation is reported. This transformation proceeds smoothly via heteroaryl sulfinate intermediates, which can be trapped in situ by various electrophiles. A broad reaction scope is demonstrated, especially for the electron-deficient heteroaryl halides. Mechanistic studies show that the radical coupling of the heteroaryl radical and sulfur dioxide radical anion may be the key step during the reaction process, as supported by EPR spectroscopy and DFT calculations.

Synthesis of 3-(Methylsulfonyl)benzo[ b]thiophenes from Methyl(2-alkynylphenyl)sulfanes and Sodium Metabisulfite via a Radical Relay Strategy

A radical relay strategy for the generation of 3-(methylsulfonyl)benzo[ b]thiophenes through a reaction of methyl(2-alkynylphenyl)sulfanes with sodium metabisulfite in the presence of a photocatalyst under visible light irradiation is developed. This photoinduced sulfonylation proceeds efficiently under mild conditions by using a catalytic amount of sodium methylsulfinate as an initiator. During the reaction process, the methyl radical generated in situ is the key intermediate, which undergoes a radical relay with the combination of sulfur dioxide to afford methylsulfonyl-containing compounds.

Manganese(iii) acetate-mediated direct C(sp2)–H-sulfonylation of enamides with sodium and lithium sulfinates

A Mn(OAc)₃ mediated oxidative C(sp²)–H sulfonylation of enamides and encarbamates with sodium and lithium sulfinates is reported.

Photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement

A photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement under visible light irradiation is developed.

Substituted Hantzsch esters as radical reservoirs with the insertion of sulfur dioxide under photoredox catalysis

A three-component reaction between 4-substituted Hantzsch esters, DABCO·(SO₂)₂, and vinyl azides in the presence of photoredox catalysts under visible light irradiation is developed. A range of (Z)-2-(alkylsulfonyl)-1-arylethen-1-amines is obtained in moderate to good yields with good regioselectivity and stereoselectivity.

Insertion of sulfur dioxide via a radical process: an efficient route to sulfonyl compounds

This review is focused on the recent advances in the chemistry of sulfur dioxide fixation through a radical process. Diverse sulfonyl compounds can be obtained efficiently under mild conditions.

Thiosulfonylation of alkenes with the insertion of sulfur dioxide under non-metallic conditions

A three-component reaction of 1-(2-allylaryl)thioureas, sulfur dioxide, and aryldiazonium tetrafluoroborates under mild conditions is realized, leading to sulfonated [3,1]-benzothiazepines in good yields. High efficiency is observed for this non-metallic transformation.

Photoinduced synthesis of (E)-vinyl sulfones through the insertion of sulfur dioxide

Under visible light irradiation, a three-component reaction of potassium alkyltrifluoroborates, sulfur dioxide and alkynes with the assistance of photocatalysis and in the presence of copper(ii) triflate is described. This transformation affords (E)-vinyl sulfones efficiently with excellent regioselectivity and stereoselectivity under mild conditions.

Recent advances in the sulfonylation of C–H bonds with the insertion of sulfur dioxide

Recent advances in the sulfonylation of C–H bonds with the insertion of sulfur dioxide are summarized. C–H bond sulfonylation under transition metal catalysis or through a radical process has been developed. In some cases, the sulfonylation can be performed under catalyst- and additive-free conditions, or can be facilitated by visible light irradiation. The efficiency is also studied by merging the radical process and metal catalysis.

C–H bond sulfonylation of anilines with the insertion of sulfur dioxide under metal-free conditions

2-Sulfonylanilines are generated in moderate to good yields through a three-component reaction of anilines, DABCO·(SO₂)₂, and aryldiazonium tetrafluoroborates under mild conditions. No metal catalysts or additives are needed for this transformation.

Benzylic C(sp3)–H bond sulfonylation of 4-methylphenols with the insertion of sulfur dioxide under photocatalysis

Sulfonylation of the benzylic C–H bond is developed through a three-component reaction of aryldiazonium tetrafluoroborates, 4-methylphenols and sodium metabisulfite (Na₂S₂O₅). The inorganic sulfite of sodium metabisulfite is used as the SO₂ surrogate.

Generation of sulfonated isobenzofuran-1(3H)-ones under photocatalysis through the insertion of sulfur dioxide

Generation of sulfonated isobenzofuran-1(3H)-ones starting from 2-vinylbenzoic acids, aryldiazonium tetrafluoroborates, and DABCO˙(SO₂)₂ under photocatalysis in the presence of visible light is achieved. Additionally, the method can be extended to 4-phenylpent-4-enoic acid and 5-phenylhex-5-enoic acid.

Intramolecular oxysulfonylation of alkenes with the insertion of sulfur dioxide under photocatalysis

Intramolecular oxysulfonylation of alkenes with the insertion of sulfur dioxide promoted by visible light is developed, leading to sulfonated tetrahydrofurans and related compounds in moderate to good yields.

A copper-catalyzed sulfonylative C–H bond functionalization from sulfur dioxide and aryldiazonium tetrafluoroborates

Sulfonylative C–H bond functionalization through a copper-catalyzed three-component reaction of 8-aminoquinoline amides, DABCO·(SO₂)₂ and aryldiazonium tetrafluoroborates is developed. Excellent selectivity in the para-position is observed.