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Biaryl scaffolds are prevalent in natural products and drug molecules, and biaryl-containing compounds have been shown to exhibit diverse and interesting biological activities. To date, numerous synthetic methods, particularly direct C–H bond activation, have been developed for the construction of such scaffolds, due to their interesting structural...
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Citations
... We used a smaller amount of Ni (0.5-2 mol%) at 70 °C (Table 2, entries [11][12][13][14], and the reaction yield was reduced under optimized conditions. Screening of various organic and inorganic bases Cs 2 CO 3 , Na 2 CO 3 , DABCO, Et 3 N, and t-BuOK showed that the K 2 CO 3 is most pleasing ( Table 2, entries [15][16][17][18][19]. ...
A water-soluble nickel complex based on amino-β-CD was developed using a facile method and exhibits excellent catalytic performance in the Suzuki reaction in water. This synthesized complex has been characterized using UV–Vis, AAS, TGA, and FT-IR techniques. The easily synthesized novel supramolecular catalysts have been applied as a green and eco-friendly catalyst in the Suzuki coupling for preparing diverse biaryls. This result indicates that using 2.5 mol% of nickel, K 2 CO 3 as the best base, and water as the green solvent are the best reaction conditions. This new catalyst features easy handling, low-cost, mild, and simple protocol. The use of low-cost and accessibility of the reagents, modest conditions, and good yields of products are notable characteristics of this method. Using aqueous media with this catalyst as a proper catalyst makes the presented process a fascinating method compared to most reports. Under mild reaction conditions, this green Ni(II)-β-CD catalyst displayed recyclable behavior seven times with minor loss in its catalytic activity.
... We hypothesized that electronrich (hetero) arenes, such as indoles and naphthol, would undergo nucleophilic addition to electrophilic pyridinium salts, leading to the formation of N-(hetero) biaryl compounds incorporating pyridine. This new approach enables the synthesis of a variety of N-(hetero) biaryl building blocks, known to be invaluable scaffolds in the sphere of medicinal chemistry (Marchais-Oberwinkler et al., 2008;Guo et al., 2011;Tsuji, T. et al., 2020;Yuan et al., 2020;Chaudhary, 2021). ...
The synthesis of heterobiaryl compounds holds significant value in organic chemistry due to their extensive range of applications. Herein, we report a highly efficient strategy for conducting C4-selective (hetero) arylation of pyridines using N-aminopyridinium salts. The reaction proceeds readily at room temperature in the presence of a base, thus eliminating the requirement for catalysts or oxidants. This method allows for the installation of various electron-rich (hetero) aryl groups on pyridines, resulting in the streamlined synthesis of highly valuable C4-(hetero) aryl pyridine derivatives, which are otherwise challenging to acquire via conventional methods. This simple and straightforward method will facilitate access to a range of heterobiaryl compounds thereby promoting their application in various scientific disciplines.
... According to an early 2,000s article, the biaryl structure exists in 4.3% of the known drugs, making it a crucial subunit for the pharmaceutical industry (2). At present, two are the main routes industrially employed to access biaryls: transition metal catalyzed reactions, e.g., classic Pd-catalyzed couplings, which offer reliable and convenient procedures, but make use of toxic substrates, i.e., boronic acids, and an unstable and precious catalyst, a Pd 0 complex (3,4), and the direct aromatization of functionalized aryl cyclohexenes via oxidative dehydrogenation (ODH) (5,6). In this case, the substrates, aryl cyclohexenes, are commercially available and easy to prepare via Grignard reactions (7,8), which makes this route more environmentally benign. ...
A metal-free route based on a carbon catalyst to synthesize biphenyls through oxidative dehydrogenation (ODH) of phenyl cyclohexene has been investigated. Among the samples examined, an air-oxidized active carbon exhibits the best activity with a 9.1 × 10-2 h-1 rate constant, yielding 74% biphenyl in 28 h at 140 °C under five bar O2 in anisole. The apparent activation energy is measured as 54.5 kJ⋅mol-1. The extended reaction scope, consisting of 15 differently substituted phenyl cyclohexenes, shows the wide applicability of the proposed method. The catalyst's good recyclability over six runs suggests this ODH method as a promising route to access the biaryl compounds. In addition, the reaction mechanism is investigated with a combination of X-ray photoelectron spectroscopy, functional group blocking, and model compounds of carbon catalysts and is proposed to be based on the redox cycle of the quinoidic groups on the carbon surface. Additional experiments prove that the addition of the catalytic amount of acid (methanesulfonic acid) accelerates the reaction. In addition, Hammett plot examination suggests the formation of a carbonium intermediate, and its possible structure is outlined.
... Biaryl compounds are privileged scaffolds applied in different chemistry fields, from drugs to materials [16]. Their synthesis remains a hot topic for organic chemistry, always looking for new synthetic pathways, including electrochemical routes. ...
Different approaches can be undertaken to realise a stereoselective electrochemical synthesis. Significant contributions to enantioselective electrochemical organic synthesis have been reported and largely reviewed in recent years. However, the development of general strategies for the electrochemical enantiocontrol of a transformation still presents considerable challenges; in particular, relatively few contributions of highly enantioselective catalytic electrochemical reactions have been reported to date. In this review article, the most recent examples of asymmetric electrochemical catalysis are discussed. The article is organised by the three types of enantioselective catalysis: metal-based catalysis, organocatalysis and biocatalysis; in each section, the most significant and recent advances are presented and discussed.
... Optimization studies were initiated with a series of CV experiments. Biphenyl 1a was selected as an appropriate model substrate, due to the high prevalence of biaryl scaffolds in biologically relevant molecules, 29 with the fluorine handle allowing facile reaction monitoring by 19 F NMR. Acetic acid was initially selected as the carboxylic acid coupling partner, due to its low cost and high availability. CV experiments indicated that benzylic substrate 1a underwent anodic oxidation preferentially to acetic acid only in the complete absence of acetate ions ( Figure S1). ...
The development of sustainable C(sp3)-H functionalization methods is of great interest to the pharmaceutical and agrochemical industries. Anodic oxidation is an efficient means of producing benzylic cations that can undergo subsequent in situ nucleophilic attack to afford functionalized benzylic products. Herein, we demonstrate the suitability of carboxylic acids as nucleophiles to yield benzylic esters. This method employs a series of secondary benzylic substrates and functionalized carboxylic acids and is demonstrated on a gram scale in flow.
... Other conditions such as microwave irradiation heating (Table 1, entry 7), 5 mol % of Pd(OAc) 2 (Table 1, entry 8) as well as 1.5, 2.5, and 3.0 equivalents of iodobenzene 13 (Table 1, entries 9-11), did not allow better results in the activation process. Notably, the optimal conditions resulted using 4.0 equivalents of iodobenzene 13, Pd(OAc) 2 (10 mol %), CuBr 2 (10 mol %) in toluene at 110°C for 24 h, affording the orthodiarylated compound 14 a in 85 % yield ( Table 1, entry 12). ...
A Pd(II)‐catalyzed C(sp²/sp³)−H bond arylation protocol has been developed to access ortho‐diaryl, ortho‐mono‐aryl, and biaryl‐diarylmethane‐glycinamide derivatives bearing picolinamide as directing group. Mechanistic details of the process have been obtained by computational modelling of the activation reaction through DFT calculations.
... Biaryl systems were demonstrated to be pluripotent scaffolds in different fields. They can be found in a wide range of natural products ( Figure 1) [1,2]; they are widely used as ligands in catalysis [3,4], and some of them are important bioactive molecules [5,6] or employed in materials [7] and agrochemicals [8]. Due to the prominent role of the biaryl scaffold, chemists in the last century have put a lot of effort into disclosing different synthetic pathways to assemble it. ...
... Thanks to the work of Gui and co-workers, it is now possible to have access to benzidine by electrochemical methods (Scheme 13) [60]. Moreover, these compounds, also known as 4,4′-diaminobiaryl, are found in various pharmaceutical products [61,62] and as building blocks for the synthesis of heterocycles [1,63]. Aliphatic and aromatic N-protected anilines were also used with EWG and EDG groups as halogens. ...
Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions.
... Biaryl moieties are ubiquitous and are utilized extensively in a variety of materials, catalytic systems, biological and pharmaceutical fields. The biaryl motifs also show high utility in various molecular switches, motors and medicines such as antibiotic, angiotensin receptor blockers (ARBs), antifungal, anticancer, anti-inflamma tory/antiarthritic, analgesic, antiemetic as well as antihypertensive drugs ( Fig. 1) [20][21][22]. Despite various achievements in the field, the C-C bond formation reaction by availing various transition metals remain the center of attraction among the scientific community [23][24][25]. ...
The report presents the fabrication and application of a highly versatile, magnetic and robust iridium based photoredox nanocatalyst. Herein, Ir(PPy)3 based photocatalyst sites have been chemically engineered over the magnetic nanoparticles to encompass the captivating features of homogeneous iridium photocatalyst with the magnetically recyclable core. A household photoreactor was designed and fabricated to achieve highly selective visible light driven oxidative C-H arylation and C-H cyanation under sustainable and ambient reaction conditions utilizing the [email protected]@ASMNPs photoredox nanocatalyst. The environment friendly [email protected]@ASMNPs shows excellent photocatalytic activity, broad substrate adaptability and outstanding recyclability compared to the analogous homogeneous catalysts. Indeed, the [email protected]@ASMNPs possess some key features including high surface area, high iridium metal loading and excellent stability. This work is expected to enlighten and provide new insights in the rational design of high performance and recoverable photoredox nanocatalyst through surface engineering strategy.
... Biaryls are core structural motifs found in commercially important natural products, agrochemicals, molecular switches, motors, polymers and ligands for catalysis [38][39][40][41][42][43][44]. Biaryls have received increased attention as privileged structures in the medicinal chemistry as they are key components of the top-selling drugs such as Losartan (angiotensin II receptor blocker used to treat hypertension), Boscalid (succinate dehydrogenase inhibitor used as broadspectrum fungicide), Biphenomicyn B (natural cyclic peptide antibiotic), Etalocib (leukotriene B4 receptor antagonist used in cancer therapy), LY503430 (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor potentiator), OSU-6162 (dopaminergic stabilizer), Mibampator (positive allosteric modulator (PAM) of the AMPA receptor used in the treatment of Parkinson's diseases) and Felbinac (non-steroidal anti-inflammatory drugs) [45,46]. ...
A novel silica supported ferrocene appended N-heterocyclic carbene-palladium complex (SilFemBenzNHC@Pd) has been prepared and characterized by using fourier transform infrared (FT-IR), fourier transform Raman (FT-Raman), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and energy dispersive X-ray analysis (EDX). This novel complex served as a robust heterogeneous catalyst for the synthesis of biaryls via homocoupling of aryl boronic acids under base-free conditions in water. Recyclability experiments were executed successfully for six successive runs.
Graphic Abstract
... The development of innovative and, most importantly, mild catalytic synthetic entries to biaryl compounds is among the most investigated research field of methodological organic chemistry [95][96][97]. Being potential axially stereogenic and chiral due to atropoisomery, biaryl compounds find in fact wide (bio)technological and biological applications, which has made them versatile and highly cherished synthetic targets. Thus, the application of enzymatic protocols to enter biaryl compounds is of great interest and represents one of the most logical, even if not trivial at all, synthetic exploitation of direct laccase oxidation of anilines and phenols (see, for instance ref [22]). ...
Laccases are multicopper oxidases, which have been widely investigated in recent decades thanks to their ability to oxidize organic substrates to the corresponding radicals while producing water at the expense of molecular oxygen. Besides their successful (bio)technological applications, for example, in textile, petrochemical, and detoxifications/bioremediations industrial processes, their synthetic potentialities for the mild and green preparation or selective modification of fine chemicals are of outstanding value in biocatalyzed organic synthesis. Accordingly, this review is focused on reporting and rationalizing some of the most recent and interesting synthetic exploitations of laccases. Applications of the so-called laccase-mediator system (LMS) for alcohol oxidation are discussed with a focus on carbohydrate chemistry and natural products modification as well as on bio- and chemo-integrated processes. The laccase-catalyzed Csp2-H bonds activation via monoelectronic oxidation is also discussed by reporting examples of enzymatic C-C and C-O radical homo- and hetero-couplings, as well as of aromatic nucleophilic substitutions of hydroquinones or quinoids. Finally, the laccase-initiated domino/cascade synthesis of valuable aromatic (hetero)cycles, elegant strategies widely documented in the literature across more than three decades, is also presented.
