Showing papers on "Reagent published in 2015"
TL;DR: In this paper, the development of catalytic systems in water in the presence of micelles obtained by addition of surfactants, focusing on the effects of these simple, economic, and green reaction media on important aspects like recyclability, activity, product and substrate selectivity.
414 citations
TL;DR: Kinetics and computational studies suggested that the high amidating reactivity of 1,4,2-dioxazol-5-one can also be attributed to the low activation energy of an imido-insertion process in addition to the high coordination ability.
Abstract: Mechanistic investigations on the Cp*Rh(III)-catalyzed direct C–H amination reaction led us to reveal the new utility of 1,4,2-dioxazol-5-one and its derivatives as highly efficient amino sources. Stepwise analysis on the C–N bond-forming process showed that competitive binding of rhodium metal center to amidating reagent or substrate is closely related to the reaction efficiency. In this line, 1,4,2-dioxazol-5-ones were observed to have a strong affinity to the cationic Rh(III) giving rise to dramatically improved amidation efficiency when compared to azides. Kinetics and computational studies suggested that the high amidating reactivity of 1,4,2-dioxazol-5-one can also be attributed to the low activation energy of an imido-insertion process in addition to the high coordination ability. While the characterization of a cationic Cp*Rh(III) complex bearing an amidating reagent was achieved, its facile conversion to an amido-inserted rhodacycle allowed for a clear picture on the C–H amidation process. The ne...
328 citations
TL;DR: A hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries and may promise a candidate for the effective separation and recovery of metal values from the sulfuric Acid Leaching liquor.
303 citations
TL;DR: A general and benign iron-catalyzed α-alkylation reaction of ketones with primary alcohols has been developed and using 2-aminobenzyl alcohol as alkylation reagent allows for the "green" synthesis of quinoline derivatives.
Abstract: A general and benign iron-catalyzed α-alkylation reaction of ketones with primary alcohols has been developed. The key to success of the reaction is the use of a Knolker-type complex as catalyst (2 mol %) in the presence of Cs2 CO3 as base (10 mol %) under hydrogen-borrowing conditions. Using 2-aminobenzyl alcohol as alkylation reagent allows for the "green" synthesis of quinoline derivatives.
208 citations
TL;DR: The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.
Abstract: Conversion of a C(sp2)–H or C(sp3)–H bond to the corresponding C–Me bond can be achieved by using AlMe3 or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.
199 citations
TL;DR: An inexpensive, thermally stable deoxyfluorination reagent is reported that fluorinates a broad range of alcohols without substantial formation of elimination side products and enables deoxy fluorination on preparatory scale.
Abstract: We report an inexpensive, thermally stable deoxyfluorination reagent that fluorinates a broad range of alcohols without substantial formation of elimination side products. This combination of selectivity, safety, and economic viability enables deoxyfluorination on preparatory scale. We employ the [18F]-labeled reagent in the first example of a no-carrier-added deoxy-radiofluorination.
187 citations
TL;DR: An N-glycan labeling reagent is developed that provides enhanced fluorescence response and MS sensitivity for glycan detection and the process of preparing a sample for analysis is simplified and combined with UHPLC HILIC chromatography and high sensitivity mass spectrometry to thoroughly detail the N- glycan profile of a monoclonal antibody.
Abstract: N-glycosylation of proteins is now routinely characterized and monitored because of its significance to the detection of disease states and the manufacturing of biopharmaceuticals. At the same time, hydrophilic interaction chromatography (HILIC) has emerged as a powerful technology for N-glycan profiling. Sample preparation techniques for N-glycan HILIC analyses have however tended to be laborious or require compromises in sensitivity. To address these shortcomings, we have developed an N-glycan labeling reagent that provides enhanced fluorescence response and MS sensitivity for glycan detection and have also simplified the process of preparing a sample for analysis. The developed labeling reagent rapidly reacts with glycosylamines upon their release from glycoproteins. Within a 5 min reaction, enzymatically released N-glycans are labeled with this reagent comprised of an NHS-carbamate reactive group, a quinoline fluorophore, and a tertiary amine for enhancing ESI+ MS ionization. To further expedite the r...
175 citations
TL;DR: The use of simple, inexpensive, and readily available reagents affords a practical synthesis of this important generic pharmaceutical, ibuprofen.
Abstract: In a total residence time of three minutes, ibuprofen was assembled from its elementary building blocks with an average yield of above 90 % for each step. A scale-up of this five-stage process (3 bond-forming steps, one work-up, and one in-line liquid–liquid separation) provided ibuprofen at a rate of 8.09 g h−1 (equivalent to 70.8 kg y−1) using a system with an overall footprint of half the size of a standard laboratory fume hood. Aside from the high throughput, several other aspects of this synthesis expand the capabilities of continuous-flow processing, including a Friedel–Crafts acylation run under neat conditions and promoted by AlCl3, an exothermic in-line quench of high concentrations of precipitation-prone AlCl3, liquid–liquid separations run at or above 200 psi to provide solvent-free product, and the use of highly aggressive oxidants, such as iodine monochloride. The use of simple, inexpensive, and readily available reagents thus affords a practical synthesis of this important generic pharmaceutical.
175 citations
TL;DR: The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross-coupling reactions, and this driving force for selectivity in oxidative coupling might also explain previous findings using HFIP and hypervalent iodine reagents.
Abstract: Solvents such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) with a high capacity for donating hydrogen bonds generate solvates that enter into selective cross-coupling reactions of aryls upon oxidation. When electric current is employed for oxidation, reagent effects can be excluded and a decoupling of nucleophilicity from oxidation potential can be achieved. The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross-coupling reactions. The shift in the redox potentials depends on the substitution pattern of the substrate employed. The concept has been expanded from arene-phenol to phenol-phenol as well as phenol-aniline cross-coupling. This driving force for selectivity in oxidative coupling might also explain previous findings using HFIP and hypervalent iodine reagents.
170 citations
TL;DR: Using the widely available DMSO as the formylation reagent under oxidative conditions, an efficient Cu-catalyzed C3-formylation reaction of imidazo[1,2-a]pyridine C-H bonds to directly generate structurally sophisticated 3- formyl imidaz[ 1, 2-a], 1-a-Pyridine derivatives has been developed.
167 citations
Patent•
25 Feb 2015
TL;DR: In this paper, the authors present methods of forming SiC/SiCN film layers on surfaces of semiconductor substrates, which may include introducing a silicon-containing film-precursor and an organometallic ligand transfer reagent into a processing chamber.
Abstract: Disclosed herein are methods of forming SiC/SiCN film layers on surfaces of semiconductor substrates. The methods may include introducing a silicon-containing film-precursor and an organometallic ligand transfer reagent into a processing chamber, adsorbing the silicon-containing film-precursor, the organometallic ligand transfer reagent, or both onto a surface of a semiconductor substrate under conditions whereby either or both form an adsorption-limited layer, and reacting the silicon-containing film-precursor with the organometallic ligand transfer reagent, after either or both have formed the adsorption-limited layer. The reaction results in the forming of the film layer. In some embodiments, a byproduct is also formed which contains substantially all of the metal of the organometallic ligand transfer reagent, and the methods may further include removing the byproduct from the processing chamber. Also disclosed herein are semiconductor processing apparatuses for forming SiC/SiCN film layers.
TL;DR: In this paper, a hydrometallurgical process for the separation and recovery of copper, manganese, cobalt, nickel and lithium from leaching liquor of spent lithium-ion batteries is presented.
TL;DR: The first example of a practical and direct trifluoromethylthiolation reaction of unactivated aliphatic CH bonds employs a silver-based reagent and is operationally simple, scalable, and proceeds under aqueous conditions in air.
Abstract: The first example of a practical and direct trifluoromethylthiolation reaction of unactivated aliphatic CH bonds employs a silver-based reagent. The reaction is operationally simple, scalable, and proceeds under aqueous conditions in air. Furthermore, its broad scope and good functional-group compatibility were demonstrated by applying this method to the selective trifluoromethylthiolation of natural products and natural-product derivatives.
TL;DR: The rhodium-catalyzed asymmetric hydroboration of α-arylenamides with BI-DIME as the chiral ligand and (Bpin)2 as the reagent yields for the first time a series ofα-amino tertiary boronic esters in good yields and excellent enantioselectivities.
Abstract: The rhodium-catalyzed asymmetric hydroboration of α-arylenamides with BI-DIME as the chiral ligand and (Bpin)2 as the reagent yields for the first time a series of α-amino tertiary boronic esters in good yields and excellent enantioselectivities (up to 99% ee)
TL;DR: This reaction represents the first hypervalent-iodine-enabled radical decarboxylative alkenylation reaction, and a novel benziodoxole-vinyl carboxylic acid reaction intermediate was isolated.
Abstract: Chemoselective C(sp(3))-C(sp(2)) coupling reactions under mild reaction conditions are useful for synthesizing alkyl-substituted alkenes having sensitive functional groups. Reported here is a visible-light-induced chemoselective alkenylation through a deboronation/decarboxylation sequence under neutral aqueous reaction conditions at room temperature. This reaction represents the first hypervalent-iodine-enabled radical decarboxylative alkenylation reaction, and a novel benziodoxole-vinyl carboxylic acid reaction intermediate was isolated. This C(sp(3))-C(sp(2)) coupling reaction leads to aryl-and acyl-substituted alkenes containing various sensitive functional groups. The excellent chemoselectivity, stable reactants, and neutral aqueous reaction conditions of the reaction suggest future biomolecule applications.
TL;DR: Calculated molecular weights, lipophilicities, and polar surface areas are presented, demonstrating the utility of the method for delivering sulfonamides with drug-like properties.
Abstract: We describe a method for the synthesis of sulfonamides through the combination of an organometallic reagent, a sulfur dioxide equivalent, and an aqueous solution of an amine under oxidative conditions (bleach). This simple reaction protocol avoids the need to employ sulfonyl chloride substrates, thus removing the limitation imposed by the commercial availability of these reagents. The resultant method allows access to new chemical space, and is also tolerant of the polar functional groups needed to impart favorable physiochemical properties required for medicinal chemistry and agrochemistry. The developed chemistry is employed in the synthesis of a targeted 70 compound array, prepared using automated methods. The array achieved a 93% success rate for compounds prepared. Calculated molecular weights, lipophilicities, and polar surface areas are presented, demonstrating the utility of the method for delivering sulfonamides with drug-like properties.
TL;DR: A simplified electrophilic trifluoromethylthiolating reagent 1c was identified that can react with a wide range of nucleophiles such as Grignard reagents, arylboronic acids, alkynes, indoles, β-ketoesters, oxindoles, and sodium sulfinates under mild reaction conditions.
Abstract: A family of electrophilic trifluoromethanesulfenates was prepared Structure–reactivity relationship studies showed that the substituted groups on the aryl ring of the trifluoromethylthiolating reagent did not have an obvious influence on their reactivities A simplified electrophilic trifluoromethylthiolating reagent 1c was then identified that can react with a wide range of nucleophiles such as Grignard reagents, arylboronic acids, alkynes, indoles, β-ketoesters, oxindoles, and sodium sulfinates under mild reaction conditions A variety of functional groups were tolerated under these conditions
TL;DR: A copper-catalyzed difunctionalizing trifluoromethylation of activated alkynes with the cheap reagent sodium trif LuOromethanesulfinate (NaSO2CF3 or Langlois' reagent) has been developed incorporating a tandem cyclization/dearomatization process.
Abstract: A copper-catalyzed difunctionalizing trifluoromethylation of activated alkynes with the cheap reagent sodium trifluoromethanesulfinate (NaSO2CF3 or Langlois' reagent) has been developed incorporating a tandem cyclization/dearomatization process. This strategy affords a straightforward route to synthesis of 3-(trifluoromethyl)-spiro[4.5]trienones, and presents an example of difunctionalization of alkynes for simultaneous formation of two carbon-carbon single bonds and one carbon-oxygen double bond.
TL;DR: A new, electrophilic difluoromethylthiophthalimide 3 was developed that allows the diffluorometHylthiolation of a wide range of nucleophiles including aryl/vinyl boronic acids, alkynes, amines, thiols, β-ketoesters, and oxindoles and electron-rich heteroarenes.
Abstract: A new, electrophilic difluoromethylthiolating reagent N-difluoromethylthiophthalimide 3 was developed. Reagent 3 can be readily synthesized in four steps from easily available starting materials phthalimide and TMSCF2H. N-difluoromethylthiophthalimide 3 is a powerful electrophilic difluoromethylthiolating reagent that allows the difluoromethylthiolation of a wide range of nucleophiles including aryl/vinyl boronic acids, alkynes, amines, thiols, β-ketoesters, and oxindoles and electron-rich heteroarenes such as indole, pyrrole, 1H-pyrrolo[2,3-b]pyridine, imidazo[1,2-a]pyridine, aminothiazole, isoxazole, and pyrazole under mild conditions.
TL;DR: A novel approach to agrochemically important difluoromethyl-substituted pyrazoles has been developed based on the elusive reagent CF2 HCHN2, which was synthesized for the first time and employed in [3+2] cycloaddition reactions with alkynes.
Abstract: A novel approach to agrochemically important difluoromethyl-substituted pyrazoles has been developed based on the elusive reagent CF2HCHN2, which was synthesized (generated in situ) for the first time and employed in [3+2] cycloaddition reactions with alkynes. The reaction is extremely practical as it is a one-pot process, does not require a catalyst or the isolation of the potentially toxic and explosive gaseous intermediate, and proceeds in a common solvent, namely chloroform, in air. The reaction is also scalable and allows for the preparation of the target pyrazoles on gram scale.
TL;DR: In this article, the chemical oxidation of benzene by Fe2+-catalyzed sodium percarbonate (SPC) was conducted, and the effects of various factors, such as the SPC/Fe2+/benzene molar ratio, temperature, order of the reagent addition, solution matrix including the presence of anions (Cl−, HCO3−, SO42− and NO3−), and the initial solution pH, were thoroughly investigated.
TL;DR: In this paper, the preparation of activated carbon from rice husk residue using H3PO4 as activation agent was studied, and the role of H 3PO4 in the activation process was discussed.
Abstract: The preparation of activated carbon from rice husk residue using H3PO4 as activation agent was studied. The samples were characterized by elemental analysis, N2 adsorption–desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), temperature programmed decomposition-mass spectra (TPD-MS), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The role of H3PO4 in the activation process was discussed. A maximum surface area of 1016 m2 g−1 was obtained under the optimized conditions, that is, a base treated solid material to H3PO4 mass ratio of 1:2, an activation temperature of 500 °C and an activation time of 1 h. H3PO4 might act as a catalyst which facilitates the release of CO2, an oxidant which reacts with carbon after dehydration, and a reagent which enters AC through C–O–P bonds.
TL;DR: The first catalytic enantio- and diastereoselective synthesis of 1,2-hydroxyboronates is reported, and Mechanistic experiments indicate control of absolute stereochemistry of the α-boryl component.
Abstract: The first catalytic enantio- and diastereoselective synthesis of 1,2-hydroxyboronates is reported. Reactions are promoted by a readily available chiral monodentate phosphoramidite–copper complex in the presence of an alkyl 1,1-diboron reagent. Products contain two contiguous stereogenic centers and are obtained in up to 91% yield, >98:2 d.r., and 98:2 e.r. The reaction is tolerant of aryl and vinyl aldehydes, and the 1,2-hydroxyboronate products can be transformed into versatile derivatives. Mechanistic experiments indicate control of absolute stereochemistry of the α-boryl component.
TL;DR: The importance of removing certain polyphenols after the enzymic reaction when using 3,5-dinitrosalicylic acid since they interfere with this reagent is shown and there was a substantial ~5-fold effect on acarbose IC50 values when working just outside optimal conditions.
TL;DR: Control experiments revealed that the presence of a sp(2) nitrogen atom at the 2-position of the substrate and the use of a boron-based reagent were crucial for the activation of the relatively inert C(aryl)-O bond of aryl 2-pyridyl ethers.
Abstract: The rhodium-catalyzed reaction of aryl 2-pyridyl ethers with a diboron reagent results in the formation of arylboronic acid derivatives via activation of the C(aryl)–O bonds. The straightforward synthesis of 1,2-disubstituted arenes was enabled through catalytic ortho C–H bond functionalization directed by the 2-pyridyloxy group followed by substitution of this group with a boryl group. Several control experiments revealed that the presence of a sp2 nitrogen atom at the 2-position of the substrate and the use of a boron-based reagent were crucial for the activation of the relatively inert C(aryl)–O bond of aryl 2-pyridyl ethers.
TL;DR: In this article, a uniform water-soluble monolayer MoS2 quantum dots (MQDs) with lateral sizes of ≈21 nm, a clearly zigzag-terminated edge, and a hexagonal lattice structure are achieved using ammonium molybdate, thiourea, and N-acetyl-l-cysteine (NAC) as precursors and the capping reagent in a facile one-pot hydrothermal approach.
Abstract: Uniform water-soluble monolayer MoS2 quantum dots (MQDs) with lateral sizes of ≈21 nm, a clearly zigzag-terminated edge, and a hexagonal lattice structure are achieved using ammonium molybdate, thiourea, and N-acetyl-l-cysteine (NAC) as precursors and the capping reagent in a facile one-pot hydrothermal approach MQDs have good dispersity and high stability in aqueous suspension and exhibit a significantly larger direct bandgap (396 eV) compared to monolayer MoS2 nanosheets (189 eV) Pronounced blue-shifts in the wavelengths of both the excitonic absorption and intrinsic state emission with activated strong luminescence at room temperature beyond monolayer MoS2 nanosheets is demonstrated Unusual upconversion photoluminescence is also observed and is caused by two successive transfers of energy from the near-infrared (NIR) absorption generated by the NAC capping reagent to the hexagonal structure of MQDs Additional optical properties of MQDs may provide numerous exciting technological applications Here, MQDs are demonstrated as a highly selective fluorescent reagent for detecting tetracycline hydrochloride under UV and NIR irradiation
TL;DR: Attempts to use nitrous oxide (N2O, 'laughing gas') as a reagent in synthetic chemistry are summarized, it is shown that N2O can be used as an N-atom donor for the synthesis of interesting organic molecules such as triazenes and azo dyes.
Abstract: This review article summarizes efforts to use nitrous oxide (N2O, ‘laughing gas’) as a reagent in synthetic chemistry. The focus will be on reactions which are carried out in homogeneous solution under (relatively) mild conditions. First, the utilization of N2O as an oxidant is discussed. Due to the low intrinsic reactivity of N2O, selective oxidation reactions of highly reactive compounds are possible. Furthermore, it is shown that transition metal complexes can be used to catalyze oxidation reactions, in some cases with high turnover numbers. In the final part of this overview, the utilization of N2O as a building block for more complex molecules is discussed. It is shown that N2O can be used as an N-atom donor for the synthesis of interesting organic molecules such as triazenes and azo dyes.
TL;DR: The results indicated that the specific resistance to filterability (SRF) of sludge was reduced efficiently by approximately 90%, when conditioned with Fenton's reagent and lime, and the economic assessment shows that Fenton’s re agent and lime combined with ultrahigh pressure filtration system can be an economical and viable technology for sewage sludge dewatering.
TL;DR: It was concluded that the (NFC-MAA-MA) aerogel may be used as a high capacity and reusable sorbent material in heavy-metal removing processes.
TL;DR: The results indicate that the reaction proceeds at the hypervalent iodine moiety of Togni reagent, which is activated by Cu(II) species acting as a Lewis acid catalyst, and this transformation exhibited a remarkable rate enhancement upon addition of Et3N.
Abstract: We examined the mechanism of our previously reported aminotrifluoromethylation reaction, which proceeds via intramolecular cyclization of alkenylamines in the presence of the combination of copper catalyst and Togni reagent (1). Kinetic studies revealed that the initial rate of the reaction was first order with respect to Togni reagent and CuI, as well as the substrate. Changes of the 19F NMR chemical shift of Togni reagent during the reaction suggested the existence of a dynamic equilibrium involving coordination of not only Togni reagent, but also the substrate amine and the product aziridine to copper. ESI-MS analysis provided evidence of involvement of reactive Cu(II) intermediates in the catalytic cycle. Overall, our results indicate that the reaction proceeds at the hypervalent iodine moiety of Togni reagent, which is activated by Cu(II) species acting as a Lewis acid catalyst. On the basis of these mechanistic considerations, we developed an efficient synthesis of trifluoromethylated pyrrolidine de...