A Ni-catalyzed oxidative C–H/C–H cross-dehydrogenative coupling (CDC) reaction was developed for constructing various highly functionalized alkyl (aryl)-substituted thiophenes. This method employs thiophenes and aliphatic (aromatic) amides that contain an 8-aminoquinoline as a removable directing group in the presence of a silver oxidant. The approach enables the facile one-step synthesis of substituted thiophenes with high functional group compatibility via double C–H bond cleavage without affecting C–Br and C–I bonds. DFT calculations verify the importance of KH2PO4 as an additive for promoting C–H bond cleavage and support the involvement of a Ni(III) species in the reaction.

A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1 : 1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C–Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.

A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1 : 1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C–Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.

AbstractWe developed an efficient and convenient method for metal-free bromination of 8-aminoquinoline scaffolds on the C5 position that is geometrically inaccessible. And this bromination step can be followed in a one-pot manner with five kinds of C−X (X=C, O, S) cross-coupling reactions without any extra workup, such as removal of the solvent or filtration for the separation of intermediate. The reaction tolerates a wide scope of alkyl and aryl amides as well as (hetero)aryl boronic acids, generating the corresponding arylation products in good to excellent yields. Furthermore, the one-pot alkenylation, alkynylation, thiolation and phenoxylation of quinolines on the C5 position can be efficiently realized using this brominated quinoline amide molecular platform. Thus, the method shows high practical potential in industrial organic synthesis.

The surface functionality of Au38S2(SAdm)20 nanoclusters (−SAdm = adamantanethiolate) in the presence of α-, β-, and γ-cyclodextrins (CDs) is studied. The supramolecular chemistry and host–guest interactions of CDs and the protecting ligands of nanoclusters are investigated using UV-vis and NMR spectroscopies, MALDI mass spectrometry, and molecular dynamics simulations. In contrast to α- and γ-CDs, the results show that β-CDs are capable of efficiently chemisorbing onto the Au38S2(SAdm)20 nanoclusters to yield Au38S2(SAdm)20–(β-CD)2 conjugates. MD simulations revealed that two –SAdm ligands of the nanoparticle with the least steric hindrance are capable to selectively be accommodated into hydrophobic cavity of β-CDs, as furthermore confirmed by NMR spectroscopy. The conjugates largely improve the stability of the nanoclusters in the presence of strong oxidants (e.g., TBHP). Further, the electrochemical properties of Au38S2(SAdm)20 nanoclusters and Au38S2(SAdm)20–(β-CD)2 conjugates are compared. The charge transfer to the redox probe molecules (e.g., K3Fe(CN)6) in solution was monitored by cyclic voltammetry. It is found that β-CDs act as an umbrella to cover the fragile metal cores of the nanoclusters, thereby blocking direct interaction with destabilizing agents and hence quenching the charge transfer process.

•Mild reaction conditions.•Operational simplicity.•High yields.•Non-toxic and easily available starting materials.•Inexpensive catalysts.A convenient and efficient method for the synthesis of O,O-dialkyl-Se-aryl phosphoroselenoates is described via a one pot reaction of diaryl diselenide and O,O-dialkylphosphonate catalyzed by KOH assisted by a co-catalyst of calix[4]arene 3. The calix[4]arene 3 can be recycled for five times with good yields of the desired products for the reaction. This protocol provide a simple and efficient method for the synthesis of O,O-dialkyl-Se-aryl phosphoroselenoates, avoiding the use of toxic reagents and expensive catalysts.

We describe here an efficient route for the synthesis of (Z)-vinylic sulfides 3 via the highly regio- and stereoselective coupling of (Z)-1,2-bis(aryl(alkyl)thio)alkenes and Grignard reagents over a Ni catalyst under mild conditions. (Z)-Vinylic sulfides 3 are important intermediates in the synthesis of tri- and tetrasubstituted alkenes that are important construction blocks for drugs and natural products. The directing organosulfur groups (SR) can be converted to diaryl(alkyl) disulfides (RSSR) using H2O2 as oxidant, hence avoiding the waste of sulfur resources. The protocol provides a general method that is highly regio- and stereoselective for the synthesis of a diversity of tri- and tetrasubstituted alkenes.

An efficient and convenient method is developed for the remote C–H bond chalcogenation of 8-aminoquinoline scaffolds on the C5 position that is geometrically inaccessible. The protocol makes use of inexpensive CuBr2 as mediator and shows good tolerance toward numerous disulfides/diselenides and aliphatic amides, giving the corresponding products in good to excellent yield.

Nickel-catalyzed heteroarylation of the inactive methyl C(sp3)–H bond of aliphatic amide with heteroarenes is described. The method takes advantage of chelation assistance by an 8-aminoquinolinyl moiety. The synthetic reaction has good tolerance toward functional groups, and it can be used in the construction of various kinds of alkyl-substituted heteroarenes.

A highly chemo-, regio-, and stereoselective method for the synthesis of (Z)-vinylic selenosulfides and (Z)-vinylic tellurosulfides in a one-pot reaction of terminal alkynes, diaryl disulfides, and diaryl diselenides (ditellurides) catalyzed by simple base cesium hydroxide monohydrate is described. Due to the different activities of the carbon–chalcogen bonds, the target products cleave selectively and act as a kind of readily available platform molecule for the synthesis of tetrasubstituted alkenes. The mechanism of thioselenation was studied by experimental and theoretical methods.

Nickel-catalyzed thiolation of the inactivated methyl C(sp3)–H bonds of aliphatic amides with disulfide is described. It is a novel strategy for the synthesis of thioethers with the ultimate goal of generating thioether carboxylic acids with various functional groups.

Pd–Pt nanodendrites were synthesized by a facile, environment-friendly, one-pot wet-chemical method, without using any seed, template, or toxic organic solvent. The as-obtained bimetallic nanocrystals exhibited efficient catalytic activity toward ligand-free Suzuki cross-coupling reaction in ethanol aqueous solution. A series of biphenyl compounds were obtained with high yields under mild conditions. Furthermore, the catalyst could be easily recovered and reused at least 6 consecutive cycles, nearly without losing its catalytic activity.

In trace amounts, selenium (Se) participates in different physiological functions of the human body. Its biological significance is manifested in its presence as selenocysteine (Sec) in genetically encoded selenoproteins that are important in redox regulation, anti-inflammation, and cancer treatment. Recently, stimuli-responsive micelles were developed as biosensors, but there are no nanomicelle probes for the selective imaging of Sec under biological conditions (pH = 7.4). Herein, we report the design and preparation of a 2,4-dinitrobenzenesulfonyl-decorated block poly(carbonate) copolymer, viz. PMPC-Dns, for Sec imaging. We found that PMPC-Dns trapped with the fluorescent drug doxorubicin (DOX) selectively responds to Sec, while getting little interference from biological thiols, amines or alcohols. We applied the PMPC-Dns probe successfully to image endogenous Sec in cervical cancer tissues as well as in HeLa cells. In the course of these studies, we observed simultaneous release of the trapped DOX. Hence, besides Sec imaging, the probe can be used for controlled delivery of hydrophobic molecules for biomedical applications.

Commercial copolymer Luviset clear (L1), an environmentally benign and efficient ligand, was used to facilitate the catalytic performance of Cu(NO3)2 for homo-coupling of terminal alkynes. A series of substituted aromatic and aliphatic terminal alkynes were investigated. It was found that Cu(NO3)2@L1 can catalyze the C–C coupling reactions without any other base, and the corresponding diynes are generated in good to excellent yield. X-ray photoelectron spectroscopy was used to study the reaction mechanism, and the results evidence a Cu(II)/Cu(I) catalytic system. Additionally, the catalyst can be easily separated and reused without showing significant loss of catalytic activity.

The copper-mediated direct thiolation of carbazole derivatives with disulfides via C(sp2)–H bond cleavage was developed for synthesizing diaryl and alkyl aryl sulfides. This reaction exhibits wide tolerance toward various functional groups giving the products in good yields without any additives or ligands, and can be easily extended to the synthesis of thioethers carrying a benzo[h]quinolone, 2-phenylquinoline, or indole moiety in satisfactory yields.

•A general and mild protocol for the synthesis N-heterocyclic compounds.•Catalytic amount of [Cp2Zr(H2O)2] [OSO2C4F9]2 exhibited higher catalytic activity.•The good-to-excellent yields were obtained under solvent-free condition.•Catalyst can be reused without significant loss of activity in a test of five cycles.Zirconocene bis(perfluorobutanesulfonate) is air- and water-stable and proved to be ionic on basis of conductivity measurements. It exhibits high catalytic efficiency for the synthesis of N-heterocyclic compounds under solvent-free condition, such as benzimidazoles, benzodiazepines, dihydropyrimidinones and dihydropyridines under mild condition. Furthermore, it can be reused without loss of activity in a test of five cycles. This catalytic system affords a simple and efficient approach for the synthesis of N-heterocyclic compounds.Zirconocene bis(perfluorobutanesulfonate) is air- and water-stable and exhibits high catalytic efficiency for the synthesis of N-heterocyclic compounds. Furthermore, it can be reused without loss of activity in a test of five cycles. This catalytic system affords a simple and efficient approach for the synthesis of N-heterocyclic compounds.

A novel and efficient method for the synthesis of O-allenes and N-allenes via isomerization of terminal alkynes catalyzed by cesium hydroxide monohydrate is described. The advantages of this method include: mild reaction conditions, high yields and wide tolerance toward functional groups. The protocol provides an efficient route to O-allenes and N-allenes, which are important intermediates in organic synthetic chemistry.

An air-stable uninuclear complex of bis(isopropylcyclopentadienyl) zirconium perfluorooctane sulfonate (1a·H2O·3THF) was successfully synthesized by the reaction of (i-PrCp)2ZrCl2 with C17SO3Ag. The compound 1a·H2O·3THF was characterized by different techniques (such as X-ray single crystal diffraction, TG-DSC, conductivity measurement and acid strength) and found to have the similar nature of water tolerance, air-stability, thermally-stability and strong Lewis-acidity with that of our previously reported binuclear and uninuclear zirconocenes perfluorooctanesulfonate. This novel complex was confirmed to be an effective catalyst with good recyclability and reusability for the direct benzylation of 1,3-dicarbonyl derivatives using alcohols as alkylating agents. Various 1,3-dicarbonyl and alcohols derivatives can participate in the reaction, affording the corresponding monobenzylated products in competitive yields as compared to its counterparts, such as Cp2Zr(OSO17)2·3H2O·THF and the traditional Lewis-acid catalysts.

Two air-stable novel Lewis acids of triphenylantimony(V) pentafluorbezenesulfonates (2) and perfluorooctanesulfonates (3) were successfully synthesized and characterized. X-ray studies and thermo-gravimetric analysis found that these complexes showed high anti-hydrolyzability and thermal stability. The high catalytic activity and excellent recyclability of these complexes were achieved in the Michael addition reaction and the allylation reaction. On account of their stability, storability, as well as catalytic efficiency, these complexes should find a broad range of utility in organic synthesis.

A series of strong Lewis acid air-stable titanocene perfluoroalkyl(aryl)sulfonate complexes Cp2Ti(OH2)2(OSO2X)2·THF (X = C8F17, 1·THF; X = C4F9, 2·H2O·THF; X = C6F5, 3) were successfully synthesized by the treatment of Cp2TiCl2 with C8F17SO3Ag, C4F9SO3Ag and C6F5SO3Ag, respectively. In contrast to well-known titanocene bis(triflate), these complexes showed no change in open air over three months. TG-DSC analysis showed that 1·THF, 2·H2O·THF and 3 were thermally stable at 230 °C, 220 °C and 280 °C, respectively. Conductivity measurements showed that these complexes underwent ionic dissociation in CH3CN solution. X-ray analysis results confirmed that 2·H2O·THF and 3 were cationic. ESR spectra showed that the Lewis acidity of 1·THF (1.06 eV) was higher than that of Sc3+ (1.00 eV) and Y3+ (0.85 eV). UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2·H2O·THF. Fluorescence spectra showed that the Lewis acidity of 2 (λem = 477 nm) was higher than that of Sc3+ (λem = 474 nm). These complexes showed high catalytic ability in various carbon–carbon bond forming reactions. Moreover, they show good reusability. Compared with 1·THF, 2·H2O·THF and 3 exhibit higher solubility and better catalytic activity, and will find broad applications in organic synthesis.

The utilization of organoantimony (bismuth) complexes in CO2 fixation is reviewed in this article. The efficient synthesis of cyclic carbonates from CO2 and epoxides over an organoantimony(V) catalyst was first reported in 1979. After that, several organoantimony(V) complexes were found to be active for CO2 fixation. In 2009, an organoantimony(III) complex was reported as an effective CO2 absorbent and it is the only example of this kind. The study of organobismuth complexes for CO2 fixation started in 2008, and the achievements are: (i) when organobismuth oxides, hydroxides and methoxides are used as CO2 absorbents, they are converted to carbonates, and the organobismuth carbonates can be renewed as organobismuth oxides; (ii) organobismuth complexes can be used as catalysts to transform CO2 into epoxides as cyclic carbonates at room temperature in the presence of a co-catalyst such as LiI and Bu4NI; (iii) there is the development of bimetallic organobismuth complexes that show cooperative catalytic action; (iv) there is the physical fixation of CO2 by inorganic–organic bismuth complexes; and (v) CO2 insertion into the Bi–C bond of an organobismuth complex is disclosed. Most of the above catalytic systems can be considered as “electrophile–nucleophile”. In general, the synthesis of cyclic carbonates from CO2 and epoxides catalyzed by an organoantimony (bismuth) complex follows the mechanism: the complex first reacts with CO2 to form an organometallic carbonate, then the carbonate reacts with an epoxide with ring-opening by a base (e.g., n-Bu4NI).

•A facile and efficient one-pot wet chemical method was developed to synthesize Pd-Cu nanowires (NWs) using octylphenoxypolyethoxyethanol as structure-directing and stabilizing agents.•The Pd-Cu NWs shows prominent catalytic ability and durability for the Suzuki cross coupling reaction under mild conditions.•Pd-Cu NWs is stable and reusable for the reaction.The construction and design of nanomaterials are important for improving their performance. Here we present a simple one-pot wet-chemical method for the preparation of alloyed Pd-Cu nanowires using octylphenoxypolyethoxyethanol (NP-40) as structure-directing and stabilizing agents. The obtained nanocrystals display outstanding catalytic activity for ligand-free Suzuki cross coupling reaction under mild conditions, and can be easily recovered and reused for at least 5 consecutive cycles without showing significant loss of catalytic activity.Pd-Cu nanowires were facilely synthesized by a simple one-pot wet-chemical method. The nanocrystals show remarkable catalytic performance toward ligand-free Suzuki cross coupling reaction under mild conditions.Download high-res image (243KB)Download full-size image

A Ni-catalyzed oxidative C–H/C–H cross-dehydrogenative coupling (CDC) reaction was developed for constructing various highly functionalized alkyl (aryl)-substituted thiophenes. This method employs thiophenes and aliphatic (aromatic) amides that contain an 8-aminoquinoline as a removable directing group in the presence of a silver oxidant. The approach enables the facile one-step synthesis of substituted thiophenes with high functional group compatibility via double C–H bond cleavage without affecting C–Br and C–I bonds. DFT calculations verify the importance of KH2PO4 as an additive for promoting C–H bond cleavage and support the involvement of a Ni(III) species in the reaction.

The surface functionality of Au38S2(SAdm)20 nanoclusters (−SAdm = adamantanethiolate) in the presence of α-, β-, and γ-cyclodextrins (CDs) is studied. The supramolecular chemistry and host–guest interactions of CDs and the protecting ligands of nanoclusters are investigated using UV-vis and NMR spectroscopies, MALDI mass spectrometry, and molecular dynamics simulations. In contrast to α- and γ-CDs, the results show that β-CDs are capable of efficiently chemisorbing onto the Au38S2(SAdm)20 nanoclusters to yield Au38S2(SAdm)20–(β-CD)2 conjugates. MD simulations revealed that two –SAdm ligands of the nanoparticle with the least steric hindrance are capable to selectively be accommodated into hydrophobic cavity of β-CDs, as furthermore confirmed by NMR spectroscopy. The conjugates largely improve the stability of the nanoclusters in the presence of strong oxidants (e.g., TBHP). Further, the electrochemical properties of Au38S2(SAdm)20 nanoclusters and Au38S2(SAdm)20–(β-CD)2 conjugates are compared. The charge transfer to the redox probe molecules (e.g., K3Fe(CN)6) in solution was monitored by cyclic voltammetry. It is found that β-CDs act as an umbrella to cover the fragile metal cores of the nanoclusters, thereby blocking direct interaction with destabilizing agents and hence quenching the charge transfer process.

A series of strong Lewis acid air-stable titanocene perfluoroalkyl(aryl)sulfonate complexes Cp2Ti(OH2)2(OSO2X)2·THF (X = C8F17, 1·THF; X = C4F9, 2·H2O·THF; X = C6F5, 3) were successfully synthesized by the treatment of Cp2TiCl2 with C8F17SO3Ag, C4F9SO3Ag and C6F5SO3Ag, respectively. In contrast to well-known titanocene bis(triflate), these complexes showed no change in open air over three months. TG-DSC analysis showed that 1·THF, 2·H2O·THF and 3 were thermally stable at 230 °C, 220 °C and 280 °C, respectively. Conductivity measurements showed that these complexes underwent ionic dissociation in CH3CN solution. X-ray analysis results confirmed that 2·H2O·THF and 3 were cationic. ESR spectra showed that the Lewis acidity of 1·THF (1.06 eV) was higher than that of Sc3+ (1.00 eV) and Y3+ (0.85 eV). UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2·H2O·THF. Fluorescence spectra showed that the Lewis acidity of 2 (λem = 477 nm) was higher than that of Sc3+ (λem = 474 nm). These complexes showed high catalytic ability in various carbon–carbon bond forming reactions. Moreover, they show good reusability. Compared with 1·THF, 2·H2O·THF and 3 exhibit higher solubility and better catalytic activity, and will find broad applications in organic synthesis.