Nickel-Catalyzed Kumada Reaction of Tosylalkanes with Grignard Reagents to Produce Alkenes and Modified Arylketones

Trace water in a BF3·OEt2 system: a facile access to sulfinyl alkenylsulfones from alkynes and sodium sulfinates

A highly efficient and operationally simple method for the synthesis of β-sulfinyl alkenylsulfones through a BF3·OEt2-promoted reaction of alkynes and sodium sulfinates is developed, successfully avoiding the complicated anhydrous treatment before the reaction and greatly simplifying the reaction conditions. As a facile and selective route to the targets, it features good functional group compatibility, mild conditions, easily available starting materials, and excellent yields. Notably, the trace water in solvent plays a key role in promoting the reaction, which provides a more practical pathway for the utilization of the BF3·OEt2 catalytic system.

Nickel-Catalyzed Desulfonylative Reductive Cross-Coupling of Aryl Sulfones with Aryl Bromides

Herein, a nickel catalysis system for desulfonylative C(sp²)-C(sp²) reductive cross-coupling reactions of aryl sulfone derivatives with a range of aryl bromides has been established to form diverse biaryl compounds. The complex Ar-Ni(II)-SO₂CF₃ bearing a phosphine ligand through oxidative addition of aryl sulfone to Ni(0) species was isolated and confirmed by an X-ray, which provides solid evidence for the understanding of the C(Ar)-SO₂ bond activation and reaction mechanism.

Synthesis of 2,4-diarylated pyrimidines enabled by Ni-catalyzed C–sulfone bond activation

The readily available pyrimidinyl sulfones, in which the C–S bond is cleaved selectively, could serve as electrophiles in the Ni-catalyzed cross-coupling reactions to prepare 2,4-diarylated pyrimidines under mild conditions with a broad scope.

Ni-catalyzed C-S bond construction and cleavage

Sulfur-containing compounds have attracted considerable interest due to their wide-ranging applications in pharmaceuticals, agriculture, natural products, and organic materials. The development of efficient and rapid methods for the construction and transformation of sulfur-containing compounds is of great importance. Since nickel is inexpensive and has a variety of valence states, strong nucleophilicity and low energy barriers for oxidative addition, the construction and transformation of sulfur-containing compounds by nickel-catalyzed cross-coupling have become important strategies. In addition, sulfur-containing compounds have also been playing increasingly important roles in the field of cross-coupling due to their thermodynamically stable but dynamic activity. This review will focus on nickel-catalyzed construction and transformation of various sulfide-containing compounds, such as sulfides, disulfides, and hypervalent sulfur-containing compounds.

Beyond classical sulfone chemistry: metal- and photocatalytic approaches for C-S bond functionalization of sulfones

The exceptional versatility of sulfones has been extensively exploited in organic synthesis across several decades. Since the first demonstration in 2005 that sulfones can participate in Pd-catalysed Suzuki-Miyaura type reactions, tremendous advances in catalytic desulfitative functionalizations have opened a new area of research with burgeoning activity in recent years. This emerging field is displaying sulfone derivatives as a new class of substrates enabling catalytic C-C and C-X bond construction. In this review, we will discuss new facets of sulfone reactivity toward further expanding the flexibility of C-S bonds, with an emphasis on key mechanistic features. The inherent challenges confronting the development of these strategies will be presented, along with the potential application of this chemistry for the synthesis of natural products. Taken together, this knowledge should stimulate impactful improvements on the use of sulfones in catalytic desulfitative C-C and C-X bond formation. A main goal of this article is to bring this technology to the mainstream catalysis practice and to serve as inspiration for new perspectives in catalytic transformations.

Redox-active alkylsulfones as precursors for alkyl radicals under photoredox catalysis

Visible-light photoredox catalytic method for the generation of alkyl radicals using redox-active alkylsulfones to form a new C–C bond is reported.

Expeditious and Efficient ortho-Selective Trifluoromethane-sulfonylation of Arylhydroxylamines

A metal- and oxidant-free, practical and efficient method for the synthesis of highly versatile and synthetically useful ortho-trifluoromethanesulfonylated anilines from arylhydroxylamines and trifluoromethanesulfinic chloride was developed. This rapid transformation proceeded smoothly with good yields and excellent ortho-selectivity in the absence of any metals or ligands. Mechanistically, the reaction comprised a noncanonical O-trifluoromethanesulfinylation of the arylhydroxylamine, and the subsequent [2,3]-sigmatropic rearrangement to afford ortho-trifluoromethanesulfonylated aniline derivatives. The practical application of this reaction was demonstrated by further conversion into a series of functional molecules under different reaction conditions.

Selective synthesis of enol ethers via nickel-catalyzed cross coupling of α-oxy-vinylsulfones with alkylzinc reagents

We describe here a Ni-catalyzed Negishi coupling reaction to prepare 1,2-dialkyl enol ethers in a stereoconvergent fashion. This method employs readily available and bench-stable α-oxy-vinylsulfones as electrophiles. The C-sulfone bond in the α-oxy-vinylsulfone motif is cleaved chemoselectively in these reactions. The mild conditions are tolerant of a variety of functional groups on both partners, thus representing a general strategy for enol ether synthesis. This unique reactivity of α-oxy-vinylsulfones indicates their further application as electrophilic partners in cross-coupling reactions.

Base-Mediated Radical Borylation of Alkyl Sulfones

A practical and direct method was developed for the production of versatile alkylboronic esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B 2 neop 2 ), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.

Desulfonylation via Radical Process: Recent Developments in Organic Synthesis

As the "chemical chameleon", sulfonyl-containing compounds and their variants have been merged with various types of reactions for the efficient construction of diverse molecular architectures by taking advantage of their incredible reactive flexibility. Currently, their involvement in radical transformations, in which the sulfonyl group typically acts as a leaving group via selective C-S, N-S, O-S, S-S, and Se-S bond cleavage/functionalization, has facilitated new bond formation strategies which are complementary to classical two-electron cross-couplings via organometallic or ionic intermediates. Considering the great influence and synthetic potential of these novel avenues, we summarize recent advances in this rapidly expanding area by discussing the reaction designs, substrate scopes, mechanistic studies, and their limitations, outlining the state-of-the-art processes involved in radical-mediated desulfonylation and related transformations. With a specific emphasis on their synthetic applications, we believe this review will be useful for medicinal and synthetic organic chemists who are interested in radical chemistry and radical-mediated desulfonylation in particular.

Transition-Metal-Catalyzed Monofluoroalkylation: Strategies for the Synthesis of Alkyl Fluorides by C-C Bond Formation

Alkyl fluorides modulate the conformation, lipophilicity, metabolic stability, and p K a of compounds containing aliphatic motifs and, therefore, have been valuable for medicinal chemistry. Despite significant research in organofluorine chemistry, the synthesis of alkyl fluorides, especially chiral alkyl fluorides, remains a challenge. Most commonly, alkyl fluorides are prepared by the formation of C-F bonds (fluorination), and numerous strategies for nucleophilic, electrophilic, and radical fluorination have been reported in recent years. Although strategies to access alkyl fluorides by C-C bond formation (monofluoroalkylation) are inherently convergent and complexity-generating, they have studied less than methods based on fluorination. This Review provides an overview of recent developments in the synthesis of chiral (enantioenriched or racemic) secondary and tertiary alkyl fluorides by monofluoroalkylation catalyzed by transition-metal complexes. We expect this contribution will illuminate the potential of monofluoroalkylations to simplify the synthesis of complex alkyl fluorides and suggest further research directions in this growing field.

Desulfonylative Electrocarboxylation with Carbon Dioxide

Electrocarboxylation of organic halides is one of the most investigated electrochemical approaches for converting thermodynamically inert carbon dioxide (CO₂) into value-added carboxylic acids. By converting organic halides into their sulfone derivatives, we have developed a highly efficient electrochemical desulfonylative carboxylation protocol. Such a strategy takes advantage of CO₂ as the abundant C1 building block for the facile preparation of multifunctionalized carboxylic acids, including the nonsteroidal anti-inflammatory drug ibuprofen, under mild reaction conditions.

Metal-catalysed C-Het (F, O, S, N) and C-C bond arylation

The formation of C-aryl bonds has been the focus of intensive research over the last decades for the construction of complex molecules from simple, readily available feedstocks. Traditionally, these strategies involve the coupling of organohalides (I, Br, Cl) with organometallic reagents (Mg, Zn, B, Si, Sn,…) such as Kumada-Corriu, Negishi, Suzuki-Miyaura, Hiyama and Sonogashira cross-couplings. More recently, alternative methods have provided access to these products by reactions with less reactive C-Het (F, O, S, N) and C-C bonds. Compared to traditional methods, the direct cleavage and arylation of these chemical bonds, the essential link in accessible feedstocks, has become increasingly important from the viewpoint of step-economy and functional-group compatibility. This comprehensive review aims to outline the development and advances of this topic, which was organized into (1) C-F bond arylation, (2) C-O bond arylation, (3) C-S bond arylation, (4) C-N bond arylation, and (5) C-C bond arylation. Substantial attention has been paid to the strategies and mechanistic investigations. We hope that this review can trigger chemists to discover more efficient methodologies to access arylation products by cleavage of these C-Het and C-C bonds.

Nickel-Catalyzed Reductive 2-Pyridination of Aryl Iodides with Difluoromethyl 2-Pyridyl Sulfone

A novel nickel-catalyzed reductive cross-coupling between aryl iodides and difluoromethyl 2-pyridyl sulfone (2-PySO₂CF₂H) enables C(sp²)-C(sp²) bond formation through selective C(sp²)-S bond cleavage, which demonstrates the new reactivity of 2-PySO₂CF₂H reagent. This method employs readily available nickel catalyst and sulfones as cross-electrophile coupling partners, providing facile access to biaryls under mild reaction conditions without pregeneration of arylmetal reagents.

Synthesis of quaternary centres by single electron reduction and alkylation of alkylsulfones

A new method for the generation of tertiary radicals through single electron reduction of alkylsulfones promoted by Zn and 1,10-phenanthroline has been developed. These radicals could be employed in the Giese reaction, affording structurally diverse quaternary products in good yields. With the high modularity and functional group compatibility of sulfones, the utility of this method was demonstrated by intramolecular and iterative reactions to give complex structures. The radical generation process was investigated by control experiments and theoretical calculations.

A new method for the generation of tertiary radicals through single electron reduction of alkylsulfones promoted by Zn and 1,10-phenanthroline has been developed.

Ruthenium catalyzed α-methylation of sulfones with methanol as a sustainable C1 source

Methylation of sulfones bearing an α-CH bond can be easily achieved via a one-step, Ru(ii) catalyzed redox neutral reaction using methanol as a sustainable C1 building block.

Disulfonation of terminal alkynes for 1,2-bisulfonylethenes

A highly efficient and operationally simple method for the synthesis of 1,2-disulfonylethenes involving a hypervalent iodineI(iii) reagent to promote disulfonation of terminal alkynes has been developed. This protocol provides a facile and practical pathway to selectively access (E)-1,2-disulfonylethenes that features good functional group compatibility, easily available starting materials, excellent stereoselectivity, and good yields.

Alkyltriflones in the Ramberg-Bäcklund Reaction: An Efficient and Modular Synthesis of gem-Difluoroalkenes

The unprecedented synthesis of gem-difluoroalkenes through the Ramberg-Bäcklund reaction of alkyl triflones is described herein. Structurally diverse, fully substituted gem-difluoroalkenes that are difficult to prepare by other methods can be easily prepared from readily available triflones by treatment with specific Grignard reagents. Experimental and computational studies provide insight into the unique and critical role of the Grignard reagent, which serves both as a base to remove the α-proton and as a Lewis acid to assist C-F bond activation.

Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- and α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol

The B(C₆F₅)₃-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.

Copper-Catalyzed Disulfonation of Terminal Alkynes with Sodium Arylsulfinates

A novel and direct disulfonylation reaction of commercially available terminal alkynes under copper(I)/bromodifluoroacetate cocatalyst has been realized. This protocol provides a facile and practical pathway to selectively access (E)-1,2-disulfonylethenes, in which features good functional group compatibility, easily available starting materials, and excellent stereoselectivity with good yields.

Sulfinate-Engaged Nucleophilic Addition Induced Allylic Alkylation of Allenoates

A strategically novel Pd-catalyzed nucleophilic addition induced allylic alkylation reaction (NAAA) of allenoates has been successfully accomplished. By judiciously integrating ZnCl₂-promoted Michael addition with Pd-catalyzed allylic alkylation, allenoates readily undergo allyl-sunfonylation at the internal double bond, thus providing a straightforward avenue for the rapid assembly of a host of structurally diversified α-allyl-β-sufonylbut-3-enoate derivatives. The success of this transformation profits from a delicate control of the reaction kinetic of each elementary step, thanks to the synergistic interaction of Pd/Zn bimetallic system, thus suppressing either direct allylic sulfonylation or premature quenching of therein in situ generated ester enolate intermediate. Furthermore, by expanding the scope of workable Michael acceptor beyond those previously required doubly activated ones, such as methylenemalononitrile, the present work substantially enriches the repertoire of NAAA reactions.

Desulfonylative Arylation of Redox-Active Alkyl Sulfones with Aryl Bromides

We describe the development of the first reductive cross-electrophile coupling between alkyl sulfones and aryl bromides. The use of alkyl sulfones offers strategic advantages over other alkyl electrophiles as they can be incorporated into molecules in unique ways and permit α-functionalization prior to coupling. The conditions developed here enable incorporation of a wide array of aromatic rings onto (fluoro)alkyl scaffolds with broad functional group tolerance and generality, making this a practical method for late-stage diversification.

Modular radical cross-coupling with sulfones enables access to sp3-rich (fluoro)alkylated scaffolds

Cross-coupling chemistry is widely applied to carbon-carbon bond formation in the synthesis of medicines, agrochemicals, and other functional materials. Recently, single-electron-induced variants of this reaction class have proven particularly useful in the formation of C(sp²)-C(sp³) linkages, although certain compound classes have remained a challenge. Here, we report the use of sulfones to activate the alkyl coupling partner in nickel-catalyzed radical cross-coupling with aryl zinc reagents. This method's tolerance of fluoroalkyl substituents proved particularly advantageous for the streamlined preparation of pharmaceutically oriented fluorinated scaffolds that previously required multiple steps, toxic reagents, and nonmodular retrosynthetic blueprints. Five specific sulfone reagents facilitate the rapid assembly of a vast set of compounds, many of which contain challenging fluorination patterns.

Copper-Catalyzed Decarboxylative Disulfonylation of Alkynyl Carboxylic Acids with Sulfinic Acids

A copper-catalyzed decarboxylative disulfonylation of alkynyl carboxylic acids with sulfinic acids in aqueous solution has been developed. The reaction provides a straightforward and practical access to (E)-1,2-disulfonylethenes, which are important building blocks in synthetic organic chemistry, and exhibits a good functional group tolerance and excellent stereoselectivity. A possible mechanism for the transformation is proposed.

Polycyclic heteroaromatic ring construction driven by silver/cobalt co-catalyzed desulfonylative and defluorinative fragment-recombination of enol nonaflates with amidines

A novel Ag(i)/Co(ii) co-catalyzed tandem fragmentation and recombination reaction commencing from detachable nonaflates and amidines has been developed.

Striving to exploit alkyl electrophiles: challenge and choice in transition metal-catalyzed cross-coupling reactions of sulfones

Transition metal-catalyzed cross-coupling reactions of alkyl sulfones as crystalline and readily available alkyl electrophiles via a radical process are highlighted.

Acid-mediated sulfonylation of arylethynylene bromides with sodium arylsulfinates: synthesis of (E)-1,2-bis(arylsulfonyl)ethylenes and arylacetylenic sulfones

A solvent-dependent sulfonylation of arylethynylene bromides with sodium arylsulfinates to afford (E)-1,2-bis(arylsulfonyl)ethylenes and arylacetylenic sulfones is described.

Switching the Cleavage Sites in Palladium on Carbon-Catalyzed Carbon-Carbon Bond Disconnection

We have demonstrated a palladium on carbon-catalyzed approach to regioselectively alter the cleavage sites of the C-C bonds of cinnamaldehyde derivatives by a slight change in the reaction conditions in isopropanol under an O2 atmosphere. Styrene derivatives could be selectively formed by the addition of Na2CO3 in association with the dissociation of carbon monoxide, while benzaldehyde derivatives were generated by the addition of CuCl and morpholine instead of Na2CO3.

One-Pot Synthesis of Allylic Sulfones, Ketosulfones, and Triflyl Allylic Alcohols from Domino Reactions of Allylic Alcohols with Sulfinic Acid under Metal-Free Conditions

A metal-free tandem procedure by using a sulfonylation reaction of aryl allylic alcohols followed by an iodobenzenediacetate (PIDA)-promoted oxidative functionalization has been established. Allylic sulfones, γ-ketosulfones, and triflyl allylic alcohols have been constructed in a single operation. The methodology incorporates the sulfonyl (both aryl and triflyl) functionality with a simple work-up procedure.

[Pd(μ-Cl)Cl(IPr*)]2: a highly hindered pre-catalyst for the synthesis of tetra-ortho-substituted biaryls via Grignard reagent cross-coupling

The new well-defined catalyst [Pd(μ-Cl)Cl(IPr*)]₂ enables the efficient Grignard reagent cross-coupling for the synthesis of tetra-ortho-substituted biaryls.