Mild and efficient Cs2CO3-promoted synthesis of phosphonates

A mild and convenient synthesis for phosphonates using cesium carbonate (Cs₂CO₃), tetrabutylammonium iodide (TBAI) and DMF was developed at room temperature. Numerous dialkyl phosphites were screened using a diverse array of alkyl halides and these reaction conditions were found to be highly efficient producing various phosphonates exclusively in moderate to high yields.     

A mild and highly convenient chemoselective alkylation of thiols using Cs2CO3-TBAI

A mild and improved method for the synthesis of thioethers has been developed. In the presence of cesium carbonate, tetrabutylammonium iodide, and DMF, various alkyl and aryl thiols underwent S-alkylation to afford structurally diverse sulfides in high yield. Unprotected mercaptoalcohols and thioamines reacted chemoselectively at the sulfur moiety exclusively. An example of a one-pot, solid-phase synthesis of a thioether is also described.     

Ipso- or cine-substitutions of 6-haloimidazo[1,2-a]pyridine derivatives with different azoles depending on the reaction conditions

The reactivity of 6-haloimidazo[1,2-a]pyridine toward different azoles is reported. The process was shown to be highly dependent on the reaction conditions. Using copper(I) catalyst, the product of ipso substitution was obtained. In the absence of copper, with cesium carbonate in N,N-dimethylformamide, a cine substitution took place.     

Formation of copper oxide through NaNO3–KNO3 eutectic melt and its catalytic activity in the decomposition of ammonium perchlorate

The decomposition of basic copper carbonate in the presence and absence of NaNO₃–KNO₃ eutectic melt has been studied by employing isothermal TG and dynamic TG/DSC techniques. The rate constants for the decomposition in the presence of eutectic melt were found to be higher than when carbonate was heated alone. In both the cases copper oxide was found to be the end product. Catalytic activity of copper oxide obtained by the two methods were tested for the decomposition of ammonium perchlorate.     

PEG3400-Cu2O-Cs2CO3: an efficient and recyclable microwave-enhanced catalytic system for ligand-free Ullmann arylation of indole and benzimidazole

A mild, simple and efficient microwave-enhanced copper-catalyzed protocol for N-arylation using high molecular weight poly(ethylene glycol) (PEG₃₄₀₀) as a solvent is reported. Indole and benzimidazole have been N-arylated in the presence of cuprous oxide, cesium carbonate, and PEG₃₄₀₀, under microwave activation, with no supplementary ligands. Simple treatment by precipitation in Et₂O and filtration provided the expected product after evaporation and recovery of the catalytic system as a precipitate. The recovery and one successful re-use of the catalytic system is also described. The formation of copper-based nanoparticles was demonstrated by TEM analysis.     

Synthesis of N2-arylaminopyrimidine-5-carbonitrile derivatives via SNAr amination reaction

An efficient and high-yielding synthesis of N~2-arylaminopyrimidine-5-carbonitrile derivatives starting from arylamines and 2-methylthio-pyrimidine-5-carbonitriIe derivatives has been developed in the presence of cesium carbonate as basic reagent.This new protocol showed high chemical tolerance for a range of functional groups,and only the methylthio substituent on C2 of the pyrimidine ring was replaced with arylamine derivatives under the reaction conditions.     

Vinyl aryl ethers from copper-catalyzed coupling of vinyl halides and phenols

A general procedure for vinyl aryl ether bond formation by direct coupling of vinyl halides and phenols under mild Ullmann-type reaction conditions has been developed. Using copper chloride as the catalyst and cesium carbonate as the base, vinyl bromides or iodides were reacted with phenols in refluxing toluene to produce vinyl aryl ethers in good to excellent yields.     

Effect of microwave heating on Ullmann-type heterocycle-aryl ether synthesis using chloro-heterocycles

Ullmann ether synthesis was conducted on a variety of chloro-heterocycles with different phenols using optimized conditions involving copper powder and cesium carbonate. On many substrates, microwave heating afforded higher yields in significantly shorter reaction times compared to conventional heating conditions. These findings provide a facile method for aryl ether synthesis from chloropyridines, chloroquinolines, and chlorobenzothiazoles.     

Asymmetric total synthesis and absolute stereochemistry of the neuroactive marine macrolide palmyrolide A

The first asymmetric total synthesis and determination of the absolute configuration for the neuroactive marine macrolide palmyrolide A is described. The highlight of the synthesis is macrocyclization via trans-enamide formation catalyzed by copper(I) iodide and cesium carbonate. Comparison with the authentic spectral data confirms the synthesis of (+)-ent-palmyrolide A.     

Mild and efficient synthesis of carbazates and dithiocarbazates via a three-component coupling using Cs2CO3 and TBAI

Efficient methods for the synthesis of carbazates and dithiocarbazates have been developed. In the presence of cesium carbonate (Cs₂CO₃) and tetrabutylammonium iodide (TBAI) a hydrazine, CO₂ or CS₂, and an alkyl halide underwent a three-component coupling at room temperature. Various unprotected hydrazines and alkyl halides were examined and the results demonstrated this methodology was highly chemoselective. Applications toward the synthesis of azadepsipeptides and other pseudopeptides are described.     

Sorption of cesium on copper hexacyanoferrate/polymer/silica composites in batch and dynamic conditions

The sorption of cesium ions from aqueous solutions on composite sorbents was investigated in static (by the batch method) and dynamic (on column) conditions. The composite sorbents consisted of copper hexacyanoferrate retained by an anion-exchange polymeric layer bound to porous silica beads. The influence of cesium concentration and solution flow rates on cesium sorption were studied. The cesium sorption isotherm obtained is of the Langmuir type. The shape of the breakthrough curves and the sorption capacity for cesium depend on the preparation procedure of the composites.     

Cesium Carbonate in Weakly Hydrated Solid/Liquid Heterogeneous Medium: A New Reagent for Anionic Activation Synthesis

Transformation of acidic hydrogen carrying aldehydes- in corresponding ethylenic esters or ethers is carried out in the presence of cesium carbonate. Cesium carbonate proves to be an efficient reagent for any transformation by anionic activation of poly-functional molecules.     

Ullmann diaryl ether synthesis: rate acceleration by 2,2,6,6-tetramethylheptane-3,5-dione

[reaction: see text]. In the copper salt catalyzed ether formation from aryl bromides or iodides and phenols, 2,2,6,6-tetramethylheptane-3,5-dione (TMHD) was found to greatly accelerate the ordinarily difficult reaction, making it occur under more moderate temperatures and reaction times. A series of aryl halides and phenols were shown to form ethers in NMP as the solvent, cesium carbonate as the base, and CuCl and TMHD as the catalysts. The reaction was shown to tolerate electron-rich aryl bromides and electron-neutral phenols.     

Standard enthalpies of formation of Sr2CuO3 and Ca2CuO3

The enthalpies of reactions between alkaline-earth cuprates M₂CuO₃ (M = Ca, Sr) and hydrochloric acid were measured in a hermetic swinging calorimeter at 298.15 K. The M₂CuO₃ samples were prepared by solid-phase synthesis from calcium or strontium carbonate and copper oxide and characterized by X-ray powder diffraction, EDX and wet analysis. The standard enthalpies of formation obtained for the cuprates, −1431 ± 4 kJ mol⁻¹ for Ca₂CuO₃ and −1374 ± 3 kJ mol⁻¹ for Sr₂CuO₃, are discussed and compared with previous experimental and assessed values.     

Controlled-potential electrolysis of copper foil and graphite-coated copper foil in a nonaqueous 1 M LiPF6 in a ternary organic carbonate solvent

Controlled-potential electrolysis of battery-grade copper foil and graphite-coated copper foil electrodes in a typical lithium ion battery electrolyte (1 M LiPF₆ in propylene carbonate:ethylene carbonate:dimethyl carbonate [1:1:3 vol.]) was performed in order to construct Tafel plots to obtain values of the exchange current, i₀, and transfer coefficient, α. The transfer coefficients of both electrodes were found to be small (α = 0.25), which was consistent with an assumption of a dominant anodic process in the cell. At room temperature, the graphite-coated copper foil was found to have a higher exchange current than the copper foil. This can be explained by the intercalation of lithium ions into the graphite coating which increases the electron transfer rate. In the range of 0 °C to 50 °C, the exchange currents of both electrodes increased with temperature, but at different rates, while the transfer coefficients were not significantly affected by temperature.     

Synthesis of 6-substituted imidazo[2,1-b]thiazoles via Pd/Cu-mediated Sonogashira coupling in water

The reaction of 2-amino-3-(2-propynyl)thiazolium bromide with various iodobenzenes, catalyzed by Pd/Cu, in the presence of sodium lauryl sulfate as surfactant and cesium carbonate as base, in water, leads to the formation of 6-substituted imidazo[2,1-b]thiazoles.     

Effect of alkali metal oxides on the selectivity of carbon monoxide conversion to give hydrogen on copper-containing catalysts

Possibility of synthesizing aluminum-zinc-copper catalysts by mechanochemical activation of metallic copper and zinc with ammonium carbonate, followed by introduction of γ-Al₂O₃ and promoter additives (potassium, rubidium, and cesium carbonates), hydrothermal treatment, and calcination is demonstrated. The effect of the promoter additives and preparation conditions was studied. The activity and selectivity of the samples in the reaction of steam conversion of CO was examined. The composition of by-products formed in the course of a test reaction was determined.     

Cp2TiCl2/i-BuMgBr还原断裂Se—Csp键反应研究

Cp₂TiCl₂/i-BuMgBr体系形成的钛氢化试剂与炔硒醚反应生成端炔与深蓝色钛硒化物, 后者在空气中被氧化为二醚, 与酰氯反应, 高产率地形成对应的硒代酯.     

Front Cover: Facile Multicomponent Synthesis of Oxazolidinones from Primary Amines and Cesium (Hydrogen)Carbonate (Eur. J. Org. Chem. 27/2023)

A facile multicomponent, catalyst-free oxazolidinone synthesis from primary aliphatic or aromatic amines, dibromoethane (DBE), and the usage of either cesium carbonate or cesium hydrogencarbonate as the simultaneous base and C1 source is reported. The applicability of this technically simple reaction was demonstrated by a broad scope with generally high yields, enabling concise late-stage functionalization of amino groups into N-substituted oxazolidinones. The proposed operating reaction mechanism consists of a first-step nucleophilic substitution reaction between DBE and the primary amine, followed by the formation of a carbamate or carbonate intermediate and subsequent cyclization. Additional versatility of the herein-developed protocol has been showcased in a medicinal chemistry approach by the generation of an oxazolidinone-modified dipeptidyl peptidase 8 (DPP8) inhibitor.     

Neutron diffraction and simulation studies of CsNO3 and Cs2CO3 solutions

Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations have been used to study the structuring in aqueous solution of two cesium salts, cesium carbonate, and cesium nitrate. As was previously found for guanidinium salts of carbonate, mesoscopic-scale clusters were seen to form in the Cs2CO3 solution both in the MD simulations and in the diffraction experiments. No such large scale ion clusters were found in the CsNO3 solutions in either the modeling or experiments. The results are dominated by the strength and geometry of the direct first-neighbor interactions, which explain the differences in the clustering behavior between the two solutions without need to refer to longer-range water-water structuring.