Nickel-Catalyzed Direct Cross-Coupling of Diaryl Sulfoxide with Aryl Bromide

One-Pot Synthesis of Benzoxazoles and Sulfoxides: Complete Utilization of Diaryl Sulfoxides

Synthesis of 2-aryl benzoxazoles and aryl sulfoxide derivatives in a one-pot process has been developed via the palladium-catalyzed cross-coupling of diaryl sulfoxides with benzoxazoles, followed by trapping the remaining sulfenate anions with different electrophilic reagents. The reaction involves the C-S and C-H bond activation and the C-C and C-S bond formation. The protocol allows a broad scope of substrates, functional group tolerance, and scalability.

Palladium-Catalyzed α-Arylation of Sulfoxonium Ylides with Aryl Thianthrenium Salts via C-S and C-H Bond Activation

Diverse α-aryl α-carbonyl sulfoxonium ylides were efficiently synthesized in yields ranging from moderate to high via a palladium-catalyzed α-arylation of sulfoxonium ylides with aryl thianthrenium salts. The reactions proceeded smoothly via C-S and C-H bond functionalization, exhibiting broad substrate scope and good compatibility to various functionalities. In addition, the scale-up synthesis could be achieved, and the one-pot protocol commencing from the use of simple arene as the precursor of aryl thianthrenium salt could also be accomplished.

Palladium-catalyzed α-arylation of sulfoxonium ylides with aryl fluorosulfates

A variety of α-arylated sulfoxonium ylides could be facilely synthesized in modest to high yields through α-arylation of sulfoxonium ylides with aryl fluorosulfates via C-O bond functionalization under palladium catalysis. Reactions using readily available and bench-stable aryl fluorosulfates as effective and appealing arylating agents showed both good substrate scope and broad functionality tolerance. Important functional groups such as nitro, cyano, formyl, acetyl, methoxycarbonyl, trifluoromethoxy, fluoro, and chloro embedded in substrates remained intact during the course of the reaction, and could be subjected to downstream modification. In addition, the reaction could be readily scalable and applied in the late-stage modification of complex molecules.

Direct Cross-Couplings of Aryl Nonaflates with Aryl Bromides under Nickel Catalysis

The direct cross-couplings of aryl nonaflates with aryl bromides could be successfully accomplished by utilizing nickel as the catalyst, magnesium as the metal mediator, and lithium chloride as the additive. The reactions proceeded efficiently in THF at room temperature to produce the desired biaryls in moderate to good yields, showing both a reasonable substrate scope and functional group tolerance. Additionally, an equally good performance could be realized when the reaction was subjected to scale-up synthesis. Preliminary study suggested that the reaction presumably proceeds through the in situ formation of an arylmagnesium reagent as the key reaction intermediate.

Cross-Electrophile Coupling: Principles, Methods, and Applications in Synthesis

Cross-electrophile coupling (XEC), defined by us as the cross-coupling of two different σ-electrophiles that is driven by catalyst reduction, has seen rapid progression in recent years. As such, this review aims to summarize the field from its beginnings up until mid-2023 and to provide comprehensive coverage on synthetic methods and current state of mechanistic understanding. Chapters are split by type of bond formed, which include C(sp3)-C(sp3), C(sp2)-C(sp2), C(sp2)-C(sp3), and C(sp2)-C(sp) bond formation. Additional chapters include alkene difunctionalization, alkyne difunctionalization, and formation of carbon-heteroatom bonds. Each chapter is generally organized with an initial summary of mechanisms followed by detailed figures and notes on methodological developments and ending with application notes in synthesis. While XEC is becoming an increasingly utilized approach in synthesis, its early stage of development means that optimal catalysts, ligands, additives, and reductants are still in flux. This review has collected data on these and various other aspects of the reactions to capture the state of the field. Finally, the data collected on the papers in this review is offered as Supporting Information for readers.

Palladium Catalyzed Cyanation of Diaryl Sulfoxides

Aryl nitriles are highly versatile and useful compounds. A palladium-catalyzed cyanation of diaryl sulfoxides using bench-stable Zn(CN)2 as the cyanating reagent has been developed. The reaction proceeded well using Pd(OAc)2 as the catalyst with the inexpensive ligand PCy3 in the presence of t-BuONa. The method has a broad scope of substrates and is scalable. The regioselective cyanation of unsymmetrical diaryl sulfoxides was observed at the side of electron-deficient and more steric hindered aryl groups.

New Sulfenate Sources for Double Pallado-Catalyzed Cross-Coupling Reaction: Application in Symmetrical Biarylsulfoxide Synthesis, and Evidence of TADF Properties

Tetrahydro-4H-thiopyran-4-one 1-oxide 1 and sulfinyl-di-tert-butylpropionate 2 were reported as sources of bis-sulfenate anion and applied in a double pallado-catalyzed cross-coupling reaction for the synthesis of symmetrical biarylsulfoxides, tolerating a large array of electronic properties and bulkiness. The photophysical properties of a biarylsulfoxide have been explored, demonstrating an unreported TADF phenomenon on sulfoxide-containing scaffolds.

Magnesium-Mediated Cross-Electrophile Couplings of Aryl 2-Pyridyl Esters with Aryl Bromides for Ketone Synthesis through In Situ-Formed Arylmagnesium Intermediates

Aryl 2-pyridyl esters could efficiently undergo cross-electrophile couplings with aryl bromides with the aid of magnesium as a reducing metal in the absence of a transition-metal catalyst, leading to the unsymmetrical diaryl ketones in modest to good yields with wide functionality compatibility. In addition, the reaction could be easily scaled up and applied in the late-stage modification of biologically active molecules. Preliminary mechanistic study showed that the coupling reaction presumably proceeds through the in situ formation of arylmagnesium reagents as key intermediates.

Nickel-Catalyzed Reductive Amidation of Aryl Fluorosulfates with Isocyanates: Synthesis of Amides via C-O Bond Cleavage

With the assistance of nickel as catalyst, 2,2'-bipyridine (bpy) as ligand, and manganese as reducing metal, the reductive amidation of isocyanates with readily accessible aryl fluorosulfates could be successfully accomplished. The reactions proceeded effectively via C-O bond activation in DMF at room temperature, enabling the facile synthesis of a range of structurally diverse amides in moderate to high yields with broad functionality compatibility. In addition, the synthetic usefulness of the method was further demonstrated by applying the reaction in scale-up synthesis and the late-stage functionalization of complex molecules with biological activities.

Cross-Electrophile Couplings of Benzyl Sulfonium Salts with Thiosulfonates via C-S Bond Activation

A zinc-mediated cross-electrophile coupling of benzyl sulfonium salts with thiosulfonates via C-S bond cleavage was achieved. The reductive thiolation proceeded well under transition metal-free conditions to afford the desired benzyl sulfides in good yields, exhibiting both broad substrate scope and good functionality tolerance. In addition, the reaction could be applied to the use of selenosulfonate as an effective selenylation agent and be subjected to scale-up synthesis.

Sulfonylation of Pyridyl Phosphonium Salts with Sulfinate Salts in Aqueous Media for the Synthesis of 4-Pyridyl Sulfones via C-P Bond Cleavage

A Na2S2O8-initiated sulfonylation of pyridyl phosphonium salts with sulfinate salts in aqueous media has been developed for facile access to 4-pyridyl sulfones. The reactions, which employed pyridyl phosphonium salts as efficient pyridylation agents via C-P bond activation, showed both broad substrate generality and good functional group compatibility. In addition, the scale-up synthesis and the late-stage modification of pharmaceutically active complex molecules (e.g., loratadine, bisacodyl) could also be successfully realized.

Nickel-Catalyzed Cross-Coupling of Aryl Diazonium Salts with Aryl Bromides

Herein, we present a one-pot method for the direct cross-coupling of aryl diazonium salts and aryl bromides in an economical way that avoids the use of sensitive organometallic reagents. The reaction is accomplished with the assistance of nickel catalysts, ligands, magnesium turnings, lithium chloride, and triethylamine, avoiding the use of pre-activated organometallic reagents.

Recent trends in incorporation of CO2 into organosulfur compounds via C-S bond cleavage

Desulfurative functionalization of organosulfur compounds to form various carbon-carbon and carbon-heteroatom bonds has become established as a powerful tool in organic chemistry. In this context, desulfurative carboxylation of this class of compounds using carbon dioxide (CO2) as a sustainable and renewable source of carboxyl has recently been developed as an efficient option for the synthesis of carboxylic acid derivatives. The aim of this Focus Review is to summarize the major progress in this appealing research field with particular emphasis on the mechanistic features of the reactions. Literature has been surveyed until the end of February 2024, according to the data collected using SciFinder and Google Scholar engines.

Palladium-Catalyzed Esterification of Aryl Fluorosulfates with Aryl Formates

An efficient palladium-catalyzed carbonylation of aryl fluorosulfates with aryl formates for the facile synthesis of esters was developed. The cross-coupling reactions proceeded effectively in the presence of a palladium catalyst, phosphine ligand, and triethylamine in DMF to produce the corresponding esters in moderate to good yields. Of note, functionalities or substituents, such as nitro, cyano, methoxycarbonyl, trifluoromethyl, methylsulfonyl, trifluoromethoxy, fluoro, chloro, bromo, methyl, methoxy, N,N-dimethyl, and [1,3]dioxolyl, were well-tolerated in the reactions, which could be kept for late-stage modification. The reactions employing readily available and relatively robust aryl fluorosulfates as coupling electrophiles could potentially serve as an attractive alternative to traditional cross-couplings with the use of aryl halides and pseudohalides as substrates.

Desulfurative Functionalization of β-Acyl Allylic Sulfides with N-H Free Indoles Highly Regioselective at C3 and N1 Positions: Rapid Access to α-Branched Enones

A regiodivergent allylation of 1H-indoles highly selectively at the C3 and N1 positions with β-acyl allylic sulfides through desulfurative C-C/C-N bond-forming reactions has been developed under mild conditions. Notably, the remarkable site-selective switch can be achieved by a delicate choice of solvents and bases. This cost-efficient method displays a broad substrate scope, good functional compatibility, and excellent site-selectivity, thus offering a divergent synthesis of indole substituted α-branched enones, which possess diverse potential opportunities for further applications and derivatization.

Hydroxylation of Aryl Sulfonium Salts for Phenol Synthesis under Mild Reaction Conditions

Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47-95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions.

Iron-Mediated Reductive Amidation of Triazine Esters with Nitroarenes

A reductive amidation of triazine esters with nitroarenes by using cheap iron as a reducing metal in the presence of TMSCl in DMF was developed. The reactions proceeded efficiently under transition metal-free conditions to give the corresponding amides in moderate to good yields with good functional group compatibility. Preliminary mechanistic investigations indicated that nitrosobenzene, N-phenyl hydroxylamine, azoxybenzene, azobenzene, aniline, and N-arylformamide possibly served as the intermediates of the reaction.

Nickel-Catalyzed Direct Cross-Coupling of Unactivated Aryl Fluorides with Aryl Bromides

A nickel-catalyzed direct cross-coupling of unactivated aryl fluorides with aryl bromides is realized. The one-pot reaction, which avoids the use of preformed and sensitive organometallic reagents, proceeds effectively via C-F bond cleavage at room temperature in THF in the presence of the phosphine ligand and magnesium powder (with or without TMSCl) to produce the desired biaryls in modest to good yields.

Nickel-Catalyzed Direct Cross-Coupling of Aryl Thioether with Aryl Bromide

A straightforward cross-coupling of aryl thioether with aryl bromide with the aid of nickel salt, magnesium, and lithium chloride in tetrahydrofuran at ambient temperature was accomplished. The one-pot reactions proceeded efficiently via C-S bond cleavage to produce the desired biaryls in modest to good yields, avoiding the use of pregenerated or commercial organometallic reagents.