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Quinones represent a ubiquitous class of natural products, extensively distributed throughout nature. Within these organisms, they fulfil pivotal roles across a spectrum of metabolic processes essential to the organisms. Their privileged core structure is present in a variety of substances explored in medicinal chemistry. Modification of the central core of quinones could give rise to new substances with great potential as drug candidates. In this context, the introduction of an aryl or heteroaryl moiety on the quinone structure can be an important strategy for the development of new potentially bioactive compounds. In the present work, direct arylation methods of quinones reported in the literature are summarized, restricting the text to methods where organometallics are not used as catalysts, nor are organometallic species formed during the catalytic cycle. Radical arylation methods are presented where diazonium salts, hydrazines and arylboronic acids are used as aryl radicals' sources, thermally and photochemically generated. Polar reactions are also presented, that is, through nucleophiles and electrophiles. In most reports, rich aromatics acts as nucleophiles against naphthoquinones, whose electrophilicity is increased by an Brönsted or Lewis acid. Quinones can be the starting materials or generated in situ from phenolic precursors. [ABSTRACT FROM AUTHOR]

Fluorinated arenes play a crucial role in drug discovery, specialty materials, and medical imaging. Although several variants for Cu‐mediated nucleophilic fluorination of arylboronic acids and derivatives have been developed, these protocols rarely address the occurrence and control of protodeboronation, which greatly complicates product separation and can compromise the effectiveness of a radiotracer for in vivo imaging. Consequently, simpler and more efficient procedures are needed to allow rapid 18F/19F‐fluorination of both arylboronic acids and esters while minimizing protodeboronation. Mechanistic controls revealed that in addition to a high temperature, strong donor ligands such as acetonitrile and pyridine accentuate a Cu‐mediated protodeboronation. This observation guided the optimization of a ligandless procedure, with t‐BuOH as solvent, to activate fluoride under milder conditions at lower temperatures minimizing protodeboronation. Additionally, a new copper salt, Cu(ONf)2 was employed to further improve the fluorination efficiency. A large range of functional groups are tolerated under the new procedure, which is complete within 30 minutes at a temperature of 60 °C, and affords fluorinated arenes and heteroarenes in 39 % to 84 % yield. With minimal modifications, the protocol can also be applied in 18F‐radiofluorination, affording radiochemical conversions (RCCs) between 17 and 54 % with minimal protodeboronation compared to previously established protocols. [ABSTRACT FROM AUTHOR]

Here we describe a homocoupling reaction of arylboronic acid facilitated by silver carbonate, which proceeds smoothly in MeOH even at ambient temperature. The reaction exhibits broad functional group compatibility, affording a variety of symmetrical biaryls in satisfactory yields. Silver nanoparticles formed in situ serve as an accelerator in this process. Moreover, initial mechanistic investigations suggest that this transformation may occur via a radical mechanism. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed Suzuki–Miyaura reaction is an important synthetic strategy for the synthesis of biaryl compounds. This work describes that palladium complexes with N,O‐bidentate ligands bearing N‐oxide units from cyclic secondary amines were used as highly efficient catalysts for Suzuki–Miyaura reactions of aryl halides with arylboronic acids. The reaction exhibited good functional group compatibility, high yields, and mild conditions. More importantly, these N,O‐coordinated palladium complexes could be easily prepared and displayed excellent catalytic performance for this classic Csp2–Csp2 coupling reaction in very short time. [ABSTRACT FROM AUTHOR]

A series of acids ArB(OH)2 and Ar2BOH with an electron-withdrawing aryl group were obtained from the corresponding borates K[ArBF3] and K[Ar2BF2] by the action of MX3 (M = B, Al; X = Cl, Br) and subsequent hydrolysis. [ABSTRACT FROM AUTHOR]

A new one‐phase process for hydroarylation of C60 fullerene using arylboronic acids and a rhodium catalyst in an aromatic solvent containing soluble protic additives is described. Yields of monohydroarylated product with tert‐butanol and water as the protic additive range from 14 to 50 % depending on which arylboronic acid is used after reaction times of 4 hours or less which is a significant improvement from the outcome of reactions carried out using conditions from the literature. Accurate monitoring of reaction outcomes was achieved by a combination of UV‐Vis spectroscopy and 1H‐NMR spectroscopy: C60 conversion was determined using an analytical HPLC‐UV‐vis method employing commonly available columns for the separation, while product formation was quantified by 1H‐NMR spectroscopy with an internal standard. Moreover, two new arylboronic acids carrying 4‐alkynyl aryl substituents, synthesized using Sonogashira couplings, are reported, as well as the use of these in the hydroarylation of C60. [ABSTRACT FROM AUTHOR]

Over 30 compounds, including para-, meta-, and ortho-phenylenediboronic acids, ortho-substituted phenylboronic acids, benzenetriboronic acids, di- and triboronated thiophenes, and pyridine derivatives were investigated as potential β-lactamase inhibitors. The highest activity against KPC-type carbapenemases was found for ortho-phenylenediboronic acid 3a, which at the concentration of 8/4 mg/L reduced carbapenems' MICs up to 16/8-fold, respectively. Checkerboard assays revealed strong synergy between carbapenems and 3a with the fractional inhibitory concentrations indices of 0.1–0.32. The nitrocefin hydrolysis test and the whole cell assay with E. coli DH5α transformant carrying blaKPC-3 proved KPC enzyme being its molecular target. para-Phenylenediboronic acids efficiently potentiated carbapenems against KPC-producers and ceftazidime against AmpC-producers, whereas meta-phenylenediboronic acids enhanced only ceftazidime activity against the latter ones. Finally, the statistical analysis confirmed that ortho-phenylenediboronic acids act synergistically with carbapenems significantly stronger than other groups. Since the obtained phenylenediboronic compounds are not toxic to MRC-5 human fibroblasts at the tested concentrations, they can be considered promising scaffolds for the future development of novel KPC/AmpC inhibitors. The complexation of KPC-2 with the most representative isomeric phenylenediboronic acids 1a, 2a, and 3a was modeled by quantum mechanics/molecular mechanics calculations. Compound 3a reached the most effective configuration enabling covalent binding to the catalytic Ser70 residue. [ABSTRACT FROM AUTHOR]

[Display omitted] 'Ligand-free' Pd-catalyzed reaction between arylboronic acid and diphenylacetylene affords a set of polyphenylated olefins and 1,2,3,4-tetraphenylnaphthalene whose yields are dependent on counteranion of PdII salt and additive nature. Tetraphenylethylene and hexaphenylbuta-1,3-diene are likely formed in tandem arylation/cross-coupling reaction with the participation of hydroxo/alkoxo alkenyl Pd species, whereas 1,2,3,4-tetraphenylnaphthalene formation probably proceeds through tandem arylation/C–H activation by halide-containing alkenyl Pd complexes. [ABSTRACT FROM AUTHOR]

A new method has been developed for the synthesis of 2-(1-arylalkyl)-1,3-benzoxazoles by coupling of arylboronic acids with 2-(5-iodo-1H-1,2,3-triazol-1-yl)phenols. The proposed cascade process involves intermediate formation of 2-(1-diazoalkyl)-1,3-benzoxazoles and their reductive C–C coupling with arylboronic acids. The procedure requires no transition metal catalysis and provides up to 67% yield of the target products. [ABSTRACT FROM AUTHOR]

A highly efficient protocol was developed for the ipso hydroxylation of arylboronic acids using citric acid as an effective organocatalyst. The sustainable methodology offers good to excellent yields with in the rapid reaction time in water as a solvent media and 30% H2O2 as an oxidant. The reaction proceeds without the aid of any metal catalyst or base and is simple, safe, and clean. The current protocol enables the access to variety of phenols and is found to be tolerable to the diverse electronic substrates. Even, the devised reaction conditions have been found to be effective in the gram-scale synthesis of an API, Mequinol. [ABSTRACT FROM AUTHOR]

An efficient and practical one‐pot reaction for the synthesis of diarylmethyl anilines from easy available materials of salicylaldehydes, arylboronic acids and aromatic amines has been successfully developed. All the reactions proceed smoothly under transition‐metal‐free conditions via a p‐TSA promoted tandem Petasis borono‐Mannich/ nucleophilic substitution reaction, providing highly functionalized amines with wide functional groups in good to excellent yields. A reasonable explanation for this transformation was suggested. [ABSTRACT FROM AUTHOR]

AlCl3-mediated protodeboronation of arylboronic acids and esters is reported herein. This method features mild reaction conditions, high reaction yields, as well as short reaction times. Mechanistic studies based on 11B NMR spectroscopy suggest that it might proceed through initial boron activation by coordination of AlCl3 to the oxygen atom of arylboronic acid or ester groups. AlCl3-mediated protodeborylation of arylboronic acids and esters was reported with mild reaction conditions, high reaction yields as well as a simple work-up procedure. [ABSTRACT FROM AUTHOR]

Ni/TiO2 nanoparticles were synthesized as a separable and reusable nanocatalyst. The catalyst structure was investigated by XRD, SEM, FT–IR, and N2 adsorption–desorption isotherm analysis and then successfully applied for the synthesis of biaryl compounds through a Suzuki–Miyaura cross-coupling reaction. A wide variety of biaryl compounds were successfully synthesized through the developed catalytic process in MeOH/H2O, and all desired biaryl compounds were obtained in good to excellent yields (60–100%) after a relatively short reaction time. Fortunately, the catalyst can be readily recovered and reused for at least five runs without any significant impact on the yield of the products. [ABSTRACT FROM AUTHOR]

Complex cyclobutanes are important motifs in both bioactive molecules and natural products, yet their enantioselective preparation has not been widely explored. In this work, we describe rhodium‐catalyzed enantioselective additions of aryl and vinyl boronic acids to cyclobutenone ketals. This transformation involves enantioselective carbometalation to give cyclobutyl‐rhodium intermediates, followed by β‐oxygen elimination to afford enantioenriched enol ethers. Overall, this addition serves as a surrogate for Rh‐catalyzed 1,4‐additions to cyclobutenone. [ABSTRACT FROM AUTHOR]

We report an efficient method to prepare polysubstituted 3-hydroxypyridines from amino acids, propargyl alcohols, and arylboronic acids. The process involves Pd(0)-catalyzed anti-selective arylative cyclizations of N-propargyl-N-tosyl-aminoaldehydes with arylboronic acids ("anti-Wacker"-type cyclization), oxidation of the resulting 5-substituted-3-hydroxy-1,2,3,6-tetrahydropyridines to 3-oxo derivatives, and elimination of p-toluenesulfinic acid. This method provides diverse polysubstituted 3-hydroxypyridines, whose hydroxy group can be further substituted by a cross-coupling reaction via a triflate. [ABSTRACT FROM AUTHOR]

A practical and efficient Suzuki coupling of phenols has been developed by using trans-NiCl(o-Tol)(PCy3)2/2PCy3 as a catalyst in the presence of tosyl fluoride as an activator. The key for the direct use of phenols lies in the compatibility of the nickel catalyst with tosyl fluoride (TsF) and its sulfur(VI) fluoride exchange (SuFEx) with CAr-OH. Water has been found to improve the one-pot process remarkably. The steric and electronic effects and the functional group compatibility of the one-pot Suzuki coupling of phenols appear to be comparable to the conventional one of pre-prepared aryl tosylates. A series of electronically and sterically various biaryls could be obtained in good to excellent yields by using 3–10 mol% loading of the nickel catalyst. The applications of this one-pot procedure in chemoselective derivatization of complex molecules have been demonstrated in 3-phenylation of estradiol and estrone. [ABSTRACT FROM AUTHOR]

Over 30 compounds, including para-, meta-, and ortho-phenylenediboronic acids, ortho-substituted phenylboronic acids, benzenetriboronic acids, di- and triboronated thiophenes, and pyridine derivatives were investigated as potential β-lactamase inhibitors. The highest activity against KPC-type carbapenemases was found for ortho-phenylenediboronic acid 3a, which at the concentration of 8/4 mg/L reduced carbapenems’ MICs up to 16/8-fold, respectively. Checkerboard assays revealed strong synergy between carbapenems and 3a with the fractional inhibitory concentrations indices of 0.1–0.32. The nitrocefin hydrolysis test and the whole cell assay with E. coli DH5α transformant carrying blaKPC-3 proved KPC enzyme being its molecular target. para-Phenylenediboronic acids efficiently potentiated carbapenems against KPC-producers and ceftazidime against AmpC-producers, whereas meta-phenylenediboronic acids enhanced only ceftazidime activity against the latter ones. Finally, the statistical analysis confirmed that ortho-phenylenediboronic acids act synergistically with carbapenems significantly stronger than other groups. Since the obtained phenylenediboronic compounds are not toxic to MRC-5 human fibroblasts at the tested concentrations, they can be considered promising scaffolds for the future development of novel KPC/AmpC inhibitors. The complexation of KPC-2 with the most representative isomeric phenylenediboronic acids 1a, 2a, and 3a was modeled by quantum mechanics/molecular mechanics calculations. Compound 3a reached the most effective configuration enabling covalent binding to the catalytic Ser70 residue.

Herein, we report the synthesis of functionalized dihydro‐benzo[b]fluorenones through a manganese‐mediated cascade radical cyclization of β‐alkynyl propenones [1,6‐enynes] with arylboronic acids. In the present strategy, the in‐situ generated aryl radical undergoes chemo‐selective addition followed by 5‐exo‐trig cyclization. The reaction is emphasized by high atom‐ and step‐economy with the construction of three new C−C bonds to access the dihydrobenzo[b]fluorenones in 68–81% yield under mild reaction conditions. The synthetic efficacy of the developed method is evidenced by the construction of new C−C and C−N bonds. [ABSTRACT FROM AUTHOR]

N,N′-Diarylation of alkane- and oxaalkane-α,ω-diamines has been performed for the first time under the Chan–Lam coupling conditions using p-tolylboronic acid as a model reagent. Optimization of the conditions showed that best results were obtained with 4 equiv of p-tolylboronic acid, 3 equiv of DBU as a base, 20 mol % of copper(II) acetate as a catalyst, and a substrate concentration of 0.05 M. The arylation of oxadiamines provided better yields (up to 80%) in comparison to diamines. [ABSTRACT FROM AUTHOR]

A gold-catalysed coupling of aryldiazonium salts with arylboronic acids is described. The reactions proceed in satisfactory yields under irradiation with blue LEDs in the presence of KF and a catalytic amount of ascorbic acid. Notably, 4-nitrobenzendiazonium tetrafluoro-borate is sufficiently reactive to undergo the coupling with a variety of arylboronic acids in the absence of aryl radical initiators. The coupling is applicable for electron-donating and electron-withdrawing groups present at the para , ortho , and meta positions of both substrates. [ABSTRACT FROM AUTHOR]

Carboxylic acids are an abundant and structurally diverse class of commercially available materials, which are commonly used as stable reagents in organic synthesis. The Suzuki–Miyaura coupling reaction directly using carboxylic acid as a substrate has been rarely reported. Here, we report an efficient coupling reaction of carboxylic acids with arylboronic acids in toluene in the presence of IPrCl-Cl, Pd(OAc)2 , PPh3 , and K3 PO4 ·7H2 O at 90 °C to give the corresponding aryl ketones. [ABSTRACT FROM AUTHOR]

Fluorinated arenes play a crucial role in drug discovery, specialty materials, and medical imaging. Although several variants for Cu-mediated nucleophilic fluorination of arylboronic acids and derivatives have been developed, these protocols rarely address the occurrence and control of protodeboronation, which greatly complicates product separation and can compromise the effectiveness of a radiotracer for in vivo imaging. Consequently, simpler and more efficient procedures are needed to allow rapid 18 F/ 19 F-fluorination of both arylboronic acids and esters while minimizing protodeboronation. Mechanistic controls revealed that in addition to a high temperature, strong donor ligands such as acetonitrile and pyridine accentuate a Cu-mediated protodeboronation. This observation guided the optimization of a ligandless procedure, with t-BuOH as solvent, to activate fluoride under milder conditions at lower temperatures minimizing protodeboronation. Additionally, a new copper salt, Cu(ONf) 2 was employed to further improve the fluorination efficiency. A large range of functional groups are tolerated under the new procedure, which is complete within 30 minutes at a temperature of 60 °C, and affords fluorinated arenes and heteroarenes in 39 % to 84 % yield. With minimal modifications, the protocol can also be applied in 18 F-radiofluorination, affording radiochemical conversions (RCCs) between 17 and 54 % with minimal protodeboronation compared to previously established protocols., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The CC bond coupling reactions have a wide range of applications in the synthesis of natural substances and the synthesis of physiologically active compounds. We first prepared modified chitosan microspheres by emulsification and investigated the performance of the chitosan adsorbent for the adsorption of copper ions. We then evaluated the catalytic performance of chitosan-supported copper microspheres in the self-coupling of arylboronic acids using 4-methoxybenzene as the model substrate, while exploring a wide range of substrates including aryl boronic acid derivatives and heterocyclic arylboronic acids, including aldehyde, nitro, and aldehyde groups. The experimental results show that good to excellent yields (55%-95%) of the desired dimer products were obtained under mild conditions at room temperature and in air, and the catalytic material could be reused up to five times with no significant decrease in catalytic activity.

Herein, a method for N‐aryl amides preparation has been established through Rh(III)‐catalyzed C(sp2)−N cross‐coupling reactions of alkyl dioxazolones with arylboronic acids, heterocyclic boronic acid, and alkenyl boronic acid. This efficient and straightforward catalytic approach was featured with broad substrate scope (38 examples), good functional group compatibility, high yields (up to 99 %), and is suitable for late‐stage modification of drug molecular structures. The possible mechanism hypothesis was also accomplished. [ABSTRACT FROM AUTHOR]

The simple combination of readily available, recoverable, and recyclable magnetite (Fe3 O4) nanoparticles and an environmentally friendly oxidant (H2 O2) induced the effective functional group transformation of arylboronic acids into their corresponding phenols under mild conditions. Moreover, subsequent treatment of the reaction intermediate with appropriate electrophiles was accomplished in a one-pot system, leading to the formation of halophenols and phenolic derivatives. [ABSTRACT FROM AUTHOR]

Catalysts generated by combinations of Pd(TFA)2 and pyridine‐hydrazone ligands have been applied to 1,2 addition of arylboronic acids to aliphatic N‐carbamoyl (Cbz) hydrazones, affording protected α‐aryl monoalkylhydrazines with high enantioselectivities (37‐99% ee). Subsequent removal of the benzyloxy carbonyl protecting group provides a direct entry to free monosubstituted hydrazines, key building blocks for the synthesis of appealing 1,2‐diaza‐heterocycles, aminoacid derived hydrazides and other pharmacophores thereof. [ABSTRACT FROM AUTHOR]

Nickel-catalyzed N-arylation of C-amino-1,2,4-triazoles with arylboronic acids was studied for the first time. An efficient catalytic system based on nickel chloride and phenanthroline was developed and a new method for the preparation of 1-substituted 3(5)-arylamino-1,2,4-triazoles was proposed. [ABSTRACT FROM AUTHOR]

Suzuki–Miyaura cross‐coupling reactions of 2,2‐difluoro‐1‐(t‐butyldimethyl)silylethenyl tosylate with arylboronic acids in the presence of Pd2(dba)3 (10 mol%), SPhos (20 mol%), and Cs2CO3 (1.7 equiv) in Dioxane/H2O (10/1) at 100 °C for 6–9 h afforded the corresponding 1‐aryl‐2,2‐difluoroethenyl(t‐butyldimethyl)silanes in 61%–84% yields. This method is a nice tool for the direct introduction of 2,2‐difluoro‐1‐(t‐butyldimethyl)silylethenyl substituent onto an aromatic ring system from the easily accessible 2,2‐difluoro‐1‐(t‐butyldimethyl)silylethenyl tosylate. Addition‐elimination reactions of 1‐phenyl‐2,2‐difluoro‐ ethenyl(t‐butyldimethyl)silane with alkyllithium reagents such as n‐butyllithium and i‐propyllithuim provided highly (Z)‐stereoselective 1‐(t‐butyldimethyl)silyl‐2‐fluoro‐1‐phenyl‐1‐alkenes in good yields. [ABSTRACT FROM AUTHOR]

The use of manganese triacetate as an oxidant component in the C-4 arylations of 2-aryl-quinazoline 3-oxides with arylboronic acids- is reported. The new protocol was applied to prepare new 2,4-di-arylated quinazoline 3-oxides in good to high yields. The method was shown to tolerate various substituents on both aromatic rings, and no complications such as deoxygenation or rearrangement to quinazolin-4(3 H)-one was observed. [ABSTRACT FROM AUTHOR]

Cascade cyclocarbopalladation of the readily available aryl/alkyl-substituted propargylic amides containing an aryl iodide moiety, followed by Suzuki–Miyaura coupling with arylboronic acids, allowed an efficient regio- and stereoselective synthesis of tetrasubstituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones. Moreover, cascade cyclocarbopalladation, followed by the reaction with 2-alkynyltrifluoroacetanilides, accomplished a double cyclization to afford challenging 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones bearing a 3-indolyl substituent through aminopalladation/reductive elimination.

A practical and efficient Suzuki coupling of phenols has been developed by using trans-NiCl(o-Tol)(PCy3)2/2PCy3 as a catalyst in the presence of tosyl fluoride as an activator. The key for the direct use of phenols lies in the compatibility of the nickel catalyst with tosyl fluoride (TsF) and its sulfur(VI) fluoride exchange (SuFEx) with CAr-OH. Water has been found to improve the one-pot process remarkably. The steric and electronic effects and the functional group compatibility of the one-pot Suzuki coupling of phenols appear to be comparable to the conventional one of pre-prepared aryl tosylates. A series of electronically and sterically various biaryls could be obtained in good to excellent yields by using 3–10 mol% loading of the nickel catalyst. The applications of this one-pot procedure in chemoselective derivatization of complex molecules have been demonstrated in 3-phenylation of estradiol and estrone.

Sulfonamides are important pharmacophores found in many human and veterinary medicines. Over 70 FDA-approved drugs contain this privileged structural motif and are used to treat a wide range of conditions, from acne to typhoid fever to pneumonia in HIV/AIDS patients. Interestingly, one-fourth of currently marketed sulfonamide-containing drugs are N-(hetero)aryl sulfonamide derivatives. Therefore, looking for new methodologies for their preparation from inexpensive, easily accessible, and non-toxic starting materials is very important in organic chemistry. Aromatic nitro compounds are valuable intermediates in organic synthesis and widely serve as precursors to amines, hydroxylamines, imines, amides, aldehydes, carboxylic acids, isocyanates and various aza heterocycles. In recent years, various protocols have been established for the synthesis of N-aryl sulfonamides directly from stable and abundant nitroarenes. The purpose of this review is to provide an overview of the available literature on the synthesis of N-(hetero)aryl sulfonamides from the corresponding nitro(hetero)arenes. Literature has been surveyed from 2015 to the end of July 2020. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed 1,2‐diarylation of vinyl esters with arylboronic acids in water has been developed. This newly elaborated protocol features a good functional group tolerance and provides one‐step access to 1,2‐diarylethanol derivatives under mild reaction conditions. The presented reaction can be carried out in the water at ambient temperature without the addition of any ligands, what makes this procedure environmentally benign. The transformation occurs within a single catalytic cycle and is feasible due to the modification of transition metal catalytic activity through the influence of π‐acceptor olefin (benzoquinone) as well as water as a medium. Moreover, this protocol allows to generate entire compound libraries (highly profitable in medicinal chemistry) and utilizes sustainable arylboronic acids as coupling partners under mild conditions. It is also noted that the structure of boron moiety has a great impact on the reaction selectivity, the usage of sterically hindered esters of arylboronic acids influence the reaction course towards stilbenes. [ABSTRACT FROM AUTHOR]

In this Account, the authors describe their progress in developing catalytic asymmetric C(sp3)–C(sp3) and C(sp3)–C(sp2) cross-coupling reactions. Whereas most catalytic enantioselective transformations rely on prochiral or meso starting materials, strategies that use racemic starting materials are rare. Key features of these reactions are efficient mechanisms for deracemization. Here, the authors present copper-catalyzed alkylation and rhodium-catalyzed Suzuki–Miyaura-type arylation reactions, their underlying mechanisms, and their applications in complex-molecule syntheses. [ABSTRACT FROM AUTHOR]

The rhodium(I)-catalyzed reaction of alkynes with aryl-boronic acids in the presence of formaldehyde results in a CO-gas-free arylative dual-carbonylation to produce γ-butenolide derivatives. The simultaneous loading of phosphine-ligated and phosphine-free rhodium(I) complexes is required for efficient catalysis. The former complex catalyzes the abstraction of a carbonyl moiety from formaldehyde through the activation of its formyl C–H bond (decarbonylation) and the latter catalyzes the subsequent dual-incorporation of the resulting carbonyl unit (carbonylation). The use of larger amounts of the phosphine-ligated rhodium(I) complex generates more carbonyl units, leading to the formation γ-butenolides via the dual-incorporation of the carbonyl unit. [ABSTRACT FROM AUTHOR]

A new simple protocol for the conversion of arylboronic acids to hydroxyarenes was achieved using molecular oxygen in the presence of tetrabutylammonium borohydride under blacklight irradiation (360 nm). A radical chain mechanism in which a superoxide ion (O2−.) plays a key role is proposed. [ABSTRACT FROM AUTHOR]

Visible‐light‐driven organic reactions are environmentally friendly green chemical transformations among which photosynthetic oxidative hydroxylation of arylboronic acids to phenols has attracted increasing research interest during the very recent years. Given the efficiency and reusability of heterogeneous catalysts, COF‐JLU25, an electron‐rich COF‐based photocatalyst constructed by integrating electron‐donating blocks 1,3,6,8‐tetrakis(4‐aminophenyl)pyrene (PyTA) and 4‐[4‐(4‐formylmethyl)‐2,5‐dimethoxyphenyl] benzaldehyde (TpDA), was selected as a photocatalyst for the oxidative hydroxylation of arylboronic acids. In our studies, COF‐JLU25 demonstrated excellent photocatalytic activity with high efficiency, robust reusability, and low catalyst loading, showcasing an application potential of previously underexplored COF‐based photocatalyst composed solely of electron‐rich units. [ABSTRACT FROM AUTHOR]

A Cu/hydrazone catalysis has been applied in the oxidative coupling of arylboronic acids and aromatic thiols for the synthesis of asymmetric diaryl sulfides. The reaction features mild conditions and readily available hydrazone ligand. It works for a wide range of arylboronic acids and thiols with good to excellent yields, exhibiting great potential of such hydrazone ligands in organic synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

A nickel‐catalyzed highly γ‐regioselective arylation and carbonylative arylation of 3‐bromo‐3,3‐difluoropropene has been developed. The reaction proceeds under mild reaction conditions, providing the gem‐difluoroalkenes with high efficiency and good functional group tolerance. The resulting gem‐difluoroalkenes can serve as versatile building blocks for diversified synthesis. Preliminary mechanistic studies and density functional theory calculations reveal that both non‐radical and radical pathways are possible for the reaction, and the radical pathway is more likely. The high γ‐regioselectivity results from the β‐bromide elimination of alkylnickel(II) species or from the reductive elimination of nickel(III) species [(aryl)(CF2=CHCH2)NiIII(Ln)X]. The γ‐selective carbonylation of 3‐bromo‐3,3‐difluoropropene under 1 atm CO gas also provides a new way for nickel‐catalyzed carbonylation. [ABSTRACT FROM AUTHOR]

A modular and straightforward synthetic strategy for the preparation of α-substituted alkenyl acetals has been developed. α-Haloalkenyl acetals react smoothly with (het)aryl boronic acids, aryl boronates, or B -alkyl-9-borabicyclo[3.3.1]nonanes through Pd-catalyzed Suzuki cross-coupling under mild conditions with good to high yields. This protocol features a broad substrate scope and good functional-group compatibility, and is easily scaled up. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have emerged as a promising, inexpensive, safe, renewable, and biodegradable alternative to harmful organic solvents as a premise for the green industrial transformation. An efficient and straightforward one-pot three-component Petasis reactions of salicylaldehyde derivatives with various amines and boronic acids in the glycerol/choline chloride-based deep eutectic solvent (DES) were developed. Wide varieties of Mannich-type products were obtained in acceptable to excellent yields under mild conditions and short reaction times. The exceptional features of this procedure involve facile and environmentally friendly solvent, recyclable reaction media, and wide tolerance toward functional groups. The DES system can be recycled four times without significantly decreasing the yields.

The Suzuki–Miyaura cross-coupling reaction of 2-bromo-1,3-bis(trifluoromethyl)benzene with arylboronic acids was evaluated and determined to suffer from the formation of large amounts of boronic acid homocoupling products in conjunction with dehalogenation. Homocoupling product formation in this process likely occurs through a rare protonolysis/second transmetalation event rather than by the well-established mechanism requiring the involvement of O2. The scope of this boronic acid homocoupling reaction was investigated and shown to predominate with electron-deficient arylboronic acids. Finally, a good yield of cross-coupling products could be obtained by employing dicyclohexyl(2′,6′-dimethoxybiphenyl-2-yl)phosphine (SPhos) as the ligand. [ABSTRACT FROM AUTHOR]

Herein, we developed a copper‐mediated Chan‐Lam type O‐arylation of arylhydroxylamines with arylboronic acids to generate transient N,O‐diarylhydroxylamines that could rapidly undergo cascade [3,3]‐sigmatropic rearrangement and rearomatization to afford NOBIN (2‐amino‐2′‐hydroxy‐1,1′‐binaphthyl) analogues under mild conditions. The newly synthesized racemic biaryl products can be further resolved by a chiral DMAP‐catalyzed O‐acylation/kinetic resolution protocol. [ABSTRACT FROM AUTHOR]

An efficient strategy for the synthesis of 6-unsubstituted indolo[1,2-c]quinazolines is described. The Pd-catalyzed reaction of o-(o-aminophenylethynyl) trifluoroacetanilides with Ar–B(OH)2 afforded 2-(o-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo[1,2-c]quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar–I, Ar–Br and ArN2+BF4−, that afforded 12-arylindolo[1,2-c]quinazolin-6(5H)-ones. Moreover, 12-unsubstituted indolo[1,2-c]quinazolines can be obtained both by reacting 2-(o-aminophenyl)indoles with DMFDMA or by sequential Pd-catalyzed reaction of o-(o-aminophenylethynyl)aniline with DMFDMA.

A general method for the synthesis of five‐membered and six‐membered selenaheterocycles through Ag‐catalyzed C−Se bond‐forming reaction is reported. This reaction proceeds via intramolecular cyclization of arylboronic acids with selenium powder. Preliminary mechanism studies demonstrate that this transformation involves a selenium‐centred radical intermediate. [ABSTRACT FROM AUTHOR]

A concise and practical method was developed for the protodeboronation of arylboronic acids under mild conditions in aqueous NaClO at 100 °C. The strategy is low-cost, transition-metal-free, and base-free. [ABSTRACT FROM AUTHOR]

The development of the reactivity on carbene complexes would lead to the creation of novel synthetic strategies. We discovered herein the Pd‐catalyzed desulfurative amide formation involved Suzuki‐Miyaura coupling reaction, notably the Pd complex was generated in situ from thioureas, Ag salt and Pd catalyst. Silver salt was essential for the construction of this type of carbenes from available and stable thioureas and well participated in the catalytic cycle. We report a method for the synthesis of arylamides from arylboronic acids, which greatly enriched the application of thiourea chemistry and expanded the application of the Suzuki‐Miyaura coupling. [ABSTRACT FROM AUTHOR]