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International audience; AbstractVarious catalytic reactions under suitable conditions were used for the carbon-carbon (C-C) bond formation, such as the Kumada, Mizoroki-Heck, Sonogashira, Negishi, Stille, Suzuki-Miyaura, Hiyama, andFukuyama cross-coupling reactions. Supporting metal nanoparticles or complexes on functionalizedgraphene oxide (GO) or reduced graphene oxide (rGO) compounds provides new heterogeneous catalysts with enhanced aptitude for the formation of C-C bonds. This review highlights the applications ofmetal decorated on modified GO and rGO derivatives to form C-C bonds. We discuss briefly the generalmechanistic cycle of each reaction and the recent applications of the graphene-based nanocatalysts forthe coupling reactions, along the advantages of each catalyst.

International audience; An easy, effective and eco-friendly one-pot process for the preparation of 4H-pyran compounds has been established by using a catalytic amount of reduced graphene oxide functionalized with diethylenetriamine (rGO-DETA) in water under mild conditions. The functionalized catalyst was very effective for this one-pot reaction and provided the desired products 1a-t with good to high yields (87-97%) in short reaction times. Moreover, rGO-DETA composite could be reused for four cycles without obvious decrease of its performance. In the next step, two pyran derivatives 1f and 1h were used to synthesize the corresponding pyran-like tacrine derivatives 3f and 3h via the reaction of cyclohexanone, aluminum trichloride in reflux of 1,2-dichloroethane as solvent. Antibacterial activity of several of the prepared compounds was assessed against Gram-positive and Gram-negative bacteria by well and disk diffusion techniques. The 4H-pyran 1g and 1s (2000 μg/mL) were effective against M. luteus as Gram-positive bacterium by recording a zone of inhibition of 15 and 16 mm, respectively. 4H-pyran 1m showed a moderate antibacterial behavior against both M. luteus and S. marcescens. Pyran-like tacrine analogue 3f (50 mg/mL) displayed antibacterial behavior towards S. aureus as Gram-positive and S. marcescens as Gram-negative bacteria with zones of inhibition of 13 and 12 mm, respectively. 4H-pyran 1j featured a minimum inhibitory concentration (MIC) value 39.06 μg/mL for M. Luteus, which is the closest value to ampicillin.

This study reports the synthesis of CuO/rGO/TiO2 in coupling reaction under visible light irradiation. Its photocatalytic performance was explored in a pseudo 4-component and a domino reaction for the synthesis of benzopyranopyrimidine compounds. It can be recovered and recycled for 5 runs.

International audience; Graphene oxide (GO) was functionalized with two organic ligands, triethylenetetramine (TETA) or 2,6-diaminopyridine (DAP), followed by palladium nanoparticles (Pd NPs) for the synthesis of Pd NPs/GO-TETA and Pd NPs/GO-DAP nanocomposites, respectively. The two heterogeneous nanocomposites were fully characterized and their efficiency was investigated for C-C bond formation for the synthesis of biaryl compounds via the Suzuki cross-coupling reaction of aryl halides with arylboronic acid derivatives. The obtained results indicated that the Pd NPs/GO-TETA nanocomposite was more effective in the Suzuki coupling reaction as compared to Pd NPs/GO-DAP. Thus, the Suzuki cross-coupling reaction of different aryl halides with arylboronic acid derivatives using Pd NPs/GO-TETA nanocomposite catalyst in the presence of Na2CO3 as base in DMF/H2O (1 /1) as solvent at 90 degrees C was carried out to afford the desired biaryl compounds in high to excellent yields (81-100%) and short reaction times (10-90 min). Additionally, Pd NPs/GO-TETA nanocomposite can be recovered and reused for 8 consecutive runs without any apparent loss of its catalytic activity, proving its high stability and potential use in organic transformations. (C) 2021 Elsevier B.V. All rights reserved.

The main objective of this study concerns the sonochemical synthesis of 1,3-dioxolane derivatives using graphene oxide catalyst by applying two methods. In the first method, we described the synthesis of 1,3-dioxolane by ring-opening of epoxides in the presence of ketones catalyzed by graphene oxide (GO) under ultrasonic irradiation. In the second sonochemical procedure, we described the synthesis of 1,3-dioxolane derivatives by the reaction of 1,2-diols with ketones using same GO catalyst. Mild reaction conditions, high yields, short reaction times, reusability of catalyst and easy isolation of the products make the developed methods very useful.

International audience; Several catalytic reactions such as Ullmann, Chan–Lam, Huisgen 1,3-dipolar cycloaddition, [2 + 3] cycloaddition, condensation, and coupling reactions under suitable conditions have been used for the synthesis of fundamental structures containing a carbon–nitrogen (C–N) bond. Graphene oxide (GO) and its derivatives as heterogeneous catalysts have attracted considerable attention for the synthesis of organic building blocks. Loading of GO derivatives with copper complexes or nanoparticles, as one of the most abundant and low toxic transition metals, allowed to design new composites with predominant ability to C–N bond formation. In this review article, we present a comprehensive overview on the synthesis of building blocks containing a C–N bond such as amines, triazoles, tetrazoles, propargyl amines, imidazoles, and benzodiazepines using GO derivatives loaded with copper complexes or nanoparticles. © 2021 John Wiley and Sons, Ltd.

International audience

An efficient, simple and regioselective ring-opening reaction of epoxides with various carboxylic acids under metal-free conditions is reported. The ring-opening of epoxides takes place in the presence of graphite oxide as an efficient and available catalyst to produce the corresponding 2-hydroxy monoester and 1,2-diester derivatives in good yields. Regioselective attack of the nucleophile, short reaction times, metal-free conditions and reusability of catalyst are among the advantages of the present protocol.

International audience

International audience; A new derivative of dipodal 1,3-calix[4]arene-based chemosensor (R), which was containing several binding sites have been synthesized and characterized by NMR, IR and LC-MS spectroscopic methods. The selectivity of Rhas been investigated in aqueous methanol, resulting in fluorescence shift and selective recognition of Ag+ among 20 various alkali, alkaline earth and transition metal ions. Microstructural features of R and its complex with Ag+have been investigated by Atomic Force Microscopy (AFM). AFM images can clearly differentiate R from its complex of Ag+. Moreover; the complicated binding mode of metal-ligand complex has been explored by UV–Vis, LC-MS, FIR, Fluorescence titration, Job's plot method and theoretical approaches. Density functional theory (DFT) method at B3LYP/LANL2DZ level of theory was employed for computational studies. Theoretical calculations revealed that selectivity and specificity of R toward Ag+ could be attributed to structural conformation of 1,3-alternate-calix[4]arene scaffold and molecular electrostatic potential of its surface. Furthermore; the competitive experiments were carried out to test sensor's ability for practical uses. Finally, the efficiency of R in matrix of physiological cations was examined and showed gradual emission enhancement which makes R an ideal candidate for monitoring of Ag+ in physiological environment.

A new calix[4]arene dimer ( C4D ) has been designed and synthesized as a fluorescent chemosensor for the recognition of NADH in aqueous media. This chemosensor showed unique selectivity toward NADH over various biomolecules, with a detection limit of 24.5 nM (16.3 μg L −1 ). Moreover, the stoichiometry of the C4D -NADH complex formed was found to be 1:1 and the binding constant was calculated to be 3.74 × 10 5 M −1 .

Graphite oxide as a heterogeneous and recyclable solid acid catalyzed a simple and efficient method for the synthesis of $\beta $-amino alcohols by ring opening of epoxides with amines. This method is effective with various aromatic and aliphatic amines under solvent-free conditions. The corresponding $\beta $-amino alcohols are obtained in high yields (56%-95%) and short reaction times (15-30 min) with high regio- and chemoselectivity under metal-free conditions.

Ultrasound irradiation was successfully applied for the direct oxidative amidation of benzyl alcohols with amines into the corresponding amides using graphite oxide (GO) as an oxidative and reusable solid acid catalyst in acetonitrile as solvent at 50°C under air atmosphere. The direct oxidative amidation of benzyl alcohols takes place under mild conditions yielding the corresponding amides in good to high yields (69-95%) and short reaction times under metal-free conditions.

A facile and convenient approach for the synthesis of multi-functionalized calix[4]arenes through multi-component reactions is described. A series of five new calix[4]arene-hexaamide derivatives were synthesized, and their structures were elucidated by means of spectroscopic data. The value of this method lies in its operational simplicity, mild reaction conditions, structural diversity of products, and good yields. Furthermore, fluorescence studies demonstrated considerable binding affinity of these new calix[4]arenes toward β-lactoglobulin protein.

Sulfonated reduced graphene oxide nanosheets (rGO-SO3H) were prepared by grafting sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide (rGO) under sonochemical conditions. rGO-SO3H catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). rGO-SO3H catalyst was successfully applied as a reusable solid acid catalyst for the direct amidation of carboxylic acids with amines into the corresponding amides under ultrasonic irradiation. The direct sonochemical amidation of carboxylic acid takes place under mild conditions affording in good to high yields (56-95%) the corresponding amides in short reaction times.

Palladium nanoparticles were prepared on reduced graphene oxide (Pd NPs/rGO) by using a sonochemical procedure. Pd NPs with a mean diameter of 37 ± 22 nm were deposited on reduced graphene oxide sheets by the reaction between PdCl 4 2 − and graphene oxide (GO) under sonochemical conditions. The catalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The Pd NPs/rGO nanocomposite was successfully applied as a reusable catalyst for the reduction of benzyl alcohol derivatives into the corresponding methylene compounds in the presence of triethylsilane. The reductive dehydroxylation of benzyl alcohols takes place under mild conditions affording high yields of the corresponding methylene compounds in short reaction times.

A novel class of functionalized-calix[4]arene such as 1,4-dihydropyridine-calix[4]arene, acridine-calix[4]arene and pyrimidine-calix[4]arene were synthesized using multicomponent reaction. These compounds have been characterized by 1H NMR, 13C NMR and HRMS. Fluorescent and 1H NMR titration investigations reveal that these derivatives have the high binding constant towards the monosaccharide and disaccharide in aqueous solution. The formation of complex was also supported by electrospray mass spectrometry.

In a new approach, shape controlled synthesis of zinc oxide nanostructures were carried out using a solvothermal route assisted amino acids such as l -Lysine (lysine), l -Cysteine (cysteine) and l -Arginine (arginine) as bifunctional species with (or without) urea or oxalic acid as additives which affect the pH of the reaction. Rod, powder, particle, cube, rock candy-like, sheet, sphere, brain-like, groundnut-like and pussy willow-like morphologies were obtained through the synthetic route. Particle sizes varied from 25 nm to 4 μm. To test the application, nine ZnO nanostructures, formulated by multi-walled carbon nanotube (MWCNT) on glassy carbon electrode (GCE) were applied as new nanobiosensors for detecting glucose in a simple and inexpensive way without using any glucose oxidase or nafion. Glucose sensing accomplished in a phosphate buffer solution (PBS, pH=7) for ZnO/MWCNT/GCE samples. Results showed that in this non-enzymatic biosensor system, spherical ZnO obtained from zinc acetate/cycteine/oxalic acid synthetic route has the highest sensitivity of 64.29 μA/cm 2 mM with repeatable results. For the mentioned sensor, no interference observed in the presence of dopamine, uric acid and fructose.

A sonochemical procedure for direct oxidative esterification of aldehydes and alcohols using graphite oxide and Oxone in an alcoholic solvent is described. Mild reaction conditions, short reaction times, cost-effectiveness, and facile isolation of the products make the present system as a practical method.

A simple, efficient, and general procedure for the ring-opening of epoxides with various alcohols to give the corresponding β-alkoxy alcohols using graphite oxide (GO) as the catalyst, under very mild reaction conditions is described. The method proceeds in good to excellent yields and in short reaction times at room temperature under metal-free conditions.

One-pot condensation/oxidation of aldehydes and primary anilines into nitrones using graphite oxide (GO) and Oxone as the oxidant under very mild reaction conditions is described. The proposed method provides a direct oxidative synthesis of various nitrones in good to excellent yields under metal-free conditions in short reaction times.

An efficient and improved procedure has been developed for the conversion of oxiranes into thiiranes using sodium thiocyanate in the presence of graphite oxide under solvent-free conditions at an ambient temperature in excellent yields and in short reaction times.

A new and efficient method for the one-pot synthesis of pyridine compounds using three-component Hantzsch synthesis in high yields using graphite oxide, a readily available and inexpensive material, as a mild and efficient agent is described.

Esterification of organic acids with alcohols under mild conditions in high yields using graphite oxide, a readily available and inexpensive material, as an effective reagent is described.

Oxone, in the presence of a catalytic amount of iron(II) sulfate and graphite oxide, oxidizes efficiently alcohols into their corresponding carboxylic acid or ketone compounds at room temperature in short reaction times and in good to quantitative yields under ultrasonic irradiation.

A new approach is applied for the synthesis of novel acridine-calix[4]arene derivatives via a multicomponent reaction. These compounds have been characterised by 1H NMR, 13C NMR and HR-MS. Our binding studies between acridine-functionalised calix[4]arenes and calf thymus DNA (CT-DNA) via fluorescence titration show that these compounds have a good affinity to CT-DNA.

A facile and general procedure is presented for the one-pot synthesis of 2-aminotetrahydrothiopyrano[4,3-b]pyran-3-carbonitrile derivatives. It is based on the three-component condensation of aliphatic, aromatic, or heterocyclic aldehydes, malononitrile, and thiopyran in the presence of mesoporous amino-functionalized MCM-41 silica in ethanol. This efficient technique has the advantage of giving 2-aminotetrahydrothiopyrano[4,3-b]pyran-3-carbonitrile derivatives using a heterogeneous mesoporous reagent in high yields, in short reaction times, and offers a simple product isolation procedure.

A convenient and efficient one-pot method for the synthesis of 2-amino-tetrahydro-4H-chromene and 2-amino-4H-benzo[h]-chromene derivatives has been developed using a catalytic amount of amino-functionalized MCM-41 in aqueous medium. This efficient technique has the advantages of giving 4H-tetrahydro-chromene and 4H-benzo[h]chromene building blocks using a reusable catalyst in good to excellent yields, to be completed in short reaction times with a simple product isolation procedure.

A simple and efficient approach towards one-step synthesis of 2-amino-5-cyano-4-hydroxy-6-aryl pyrimidines has been developed. It is based on three-component condensation of aliphatic, aromatic or heterocyclic aldehydes, ethyl cyanoacetate and guanidinium carbonate in the presence of amino-functionalized SBA-15 catalyst in ethanol. In this chemical process, the tautomeric interconversion of pyrimidine derivatives has been observed. This efficient technique has the advantage to give 2-amino-pyrimidine derivatives using a heterogeneous catalyst in high yields, to be completed in short reaction times and to offer a simple product isolation procedure.

Graphite oxide (GO) was used as an effective oxidizing agent for the synthesis of aldehydes and ketones from various alcohols under ultrasonic irradiation. Under optimized conditions, quantitative yields of the products were obtained. Compared to other reagents used for the same chemical transformation, GO displays several advantages, including low cost, ease of synthesis, and high stability to ambient conditions.

Reductive cleavage of benzylic acetal, ketal and ether compounds to the corresponding alkanes using triethylsilane and a catalytic amount of palladium(II) chloride is described. The reductive reaction took place under mild conditions, affording high yields of the corresponding alkane compounds in short reaction times.

A novel and efficient one-pot method for the preparation of fused ring 3,4-dihydropyrimidin-2(1H)-ones and thiones from cyclocondensation of aldehydes, cyclic ketones and urea or thiourea using a catalytic amount of cupric chloride under mild conditions reaction is described. This new method has the advantage to give high yields, to be completed in short reaction times and simple product isolation procedure.

Various aldehydes and ketones were efficiently transformed into the corresponding amines using amine derivatives in the presence of triethylsilane and a catalytic amount of palladium on activated carbon in ethanol. The proposed method provides a one-pot synthesis of various amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.

The article reports a practical, simple, and inexpensive procedure for the synthesis of tetrahydroquinazolinone and dihydropyrimidinone derivatives from aldehydes, cyclic ketones, and urea using a catalytic amount of ammonium chloride or lithium perchlorate. The protocol provides good yields and simple workup procedure for the products. By this method, we have prepared and characterized the 4-aryl-3,4,5,6-tetrahydrobenzo[h]quinazolin-2(1H)-one (3a, c, d, f, g, j, k), 4-aryl-3,4-dihydro-1H-indeno[1,2-d]pyrimidin-2(5H)-one (3b, e, h, i), 4-aryl-5,6-dihydrobenzo[h]quinazolin-2(3H)-one (3j′, k′, l′), and 4-aryl-3,5-dihydro-2H-indeno[1,2-d]pyrimidin-2-one (3i′, m′, n′, o′, p′) derivatives. Furthermore, we have synthesized the pyrimidinone derivatives (6a′–e′) using a catalytic amount of cupric chloride from aldehydes, acyclic ketones and urea. The tautomeric interconversion of pyrimidinone derivatives 6a′–e′ ↔ 6a″–e″ has been observed.

An efficient synthesis of 1,4-dihydropyridine derivatives has been achieved by the one-pot cyclocondensation reaction of methyl 3-aminocrotonate and a range of aldehydes in the presence of chlorotrimethylsilane as a promoter under solvent-free conditions. The cyclocondenstion reaction requires a very short time and takes place in good to excellent yields. Furthermore iodotriethylsilane, generated in situ by the reaction of triethylsilane and methyl iodide in the presence of palladium chloride, has been investigated for the synthesis of 1,4-dihydropyridine derivatives. This facile and efficient method affords high yields for the preparation of 1,4-dihydropyridines at room temperature and short reaction times. Copyright © 2009 John Wiley & Sons, Ltd.

The versatility of the palladium(II) chloride and triethylsilane system has been tested in the reduction of aromatic carbonyl compounds. The reaction takes place under mild conditions. This facile and efficient method affords high yields for the reduction of aldehydes and ketones to the corresponding alkanes.

The palladium(II) chloride/triethylsilane system has been successfully applied for the selective hydrogenation of the carbon–carbon double bond of α,β-unsaturated ketones to yield the corresponding saturated carbonyl compounds. The reaction takes place under mild conditions and affords high yields.

A new and efficient method for the one-pot synthesis of pyridine compounds using three-component Hantzsch synthesis in high yields using graphite oxide, a readily available and inexpensive material, as a mild and efficient agent is described.

Depending on the predominating steric or electronic effects, the ring-opening occurs regioselectively at the higher or lower substituted carbon of the epoxide.

One-pot condensation/oxidation of aldehydes and primary anilines into nitrones using graphite oxide (GO) and Oxone as the oxidant under very mild reaction conditions is described. The proposed method provides a direct oxidative synthesis of various nitrones in good to excellent yields under metal-free conditions in short reaction times.

triethylsilane has been investigated in the hydrogenation and the isomerization of carbon–carbon double bond of 1-alkenes. The reduction of 1-alkenes was carried out in the presence of triethylsilane, ethanol and a catalytic amount of palladium(II) acetate or palladium on activated charcoal, at room temperature. This facile and efficient method affords high yields for hydrogenation of unsaturated alkenes to the corresponding alkanes. Then the carbon–carbon double bond isomerization of 1alkenes was tested using the same catalysts in the absence of solvent. The system palladium(II) acetate-triethylsilane was found to be more effective compared with palladium on an activated charcoal–triethylsilane system at room temperature, while comparable results were obtained at 50 ◦ C for both catalysts. Copyright  2006 John Wiley & Sons, Ltd.

The versatility of the palladium (II) chloride/organosilane system has been tested in the transformation of alcohols to the corresponding silyl ethers and the subsequent deprotection of triethylsilyl ethers to the parent alcohols. The reaction takes place under mild conditions and affords high yields.

Reaction of 4-amino-6-methyl-1,2,4-triazine-3-thione-5-one (AMTTO, 1) with platinum(II) chloride in THF led to the platinum complex [(AMTTO)PtCl2]3 · 4.5THF (2) in excellent yields. Treatment of 1 with palladium(II) chloride in methanol and palladium (II) bromide in THF gave the complexes [(AMTTO)PdCl2] · MeOH (3) and [(AMTTO)PdBr2]2 · 3.5THF (4), respectively. After recrystallization of 3 from methanolic solution of tetraphenylphosphonium chloride and of 4 from methanolic solution of Br2, the trimere complexes “triplexes” [(AMTTO)PdX2]3 · 8MeOH (X = Cl (5) and X = Br (6)) could be obtained. All complexes have been characterized by IR spectroscopy, elemental analyses, as well as by X-ray diffraction studies.

This paper describes the photochemical and the thermal isomerization of s-cis (E,E) 1,1-diphenly-3,4-bis(trimethylsilylmethylene)-1-silacyclopentane ( 1a ). Under thermal conditions a 1,3-sigmatropic of the methylene hydrogen occurs, yielding the s-trans isomer ( 1b ). The photochemical irradiation of ( 1a ) at 300 nm for 1 h in deoxygenated benzene gives the corresponding s-cis ( E , Z ) isomer ( 1c ) and then the s-cis ( Z , Z ) isomer ( 1d ) after prolonged irradiation (3 h). There was no evidence for the formation of the corresponding cyclobutene resulting from the ring closure of the exocylic diene.

Reduction of a variety of imine compounds with triethylsilane in the presence of catalytic amounts of palladium(II) acetate in ethanol resulted in the formation of the corresponding amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.

An efficient synthesis of 3,4‐dihydropyrimidinones from an aldehyde, a ketoester, and a urea or thiourea using a catalytic amount of ferric chloride hexahydrate is described. Microwave irradiation has been used to accelerate the synthesis of the Biginelli compounds under solvent‐free conditions and in a short reaction time and with good yield.

Isomerization of α-alkenes is carried out in the presence of a catalytic amount of palladium (II) chloride and triethylsilane at room temperature. This novel and efficient method affords high yields in the absence of solvent for double bond isomerization of alkenes.

Stilbenophanes 1c and 2c were synthesized in good yields. Among alkali ions, both isomers only formed 1:1 complexes with lithium selectively. An X-ray structure of 1c shows a statistical disorder which leads to two refined positions for the ethylene moiety. The existence of a weak intramolecular C-H > O hydrogen bond in its structure was confirmed by both X-ray analysis and theoretical calculation.