Calcined Mg-Al Layered Double Hydroxide as a Heterogeneous Catalyst for the Synthesis of Urea Derivatives from Amines and CO2

The calcined Mg‐Al layered double hydroxides (LDHs) with a Mg/Al molar ratio of 3:1 were synthesized and characterized thoroughly by X‐ray diffraction (XRD), temperature‐programmed desorption (TPD) of CO₂, and thermogravimetric analysis (TGA). Thus the calcined Mg‐Al LDHs were used as catalyst for the catalytic synthesis of disubstituted ureas from amines and CO₂. The effects of reaction time, reaction temperature, pressure, solvent and calcined temperature on activity have been investigated. The results indicated that aliphatic amines, cyclohexylamine and benzylamine can be converted to the corresponding ureas selectively over the calcined Mg‐Al LDHs catalysts with N‐methyl‐2‐pyrrolidone (NMP) as solvent without using any dehydrating regent. The catalyst can be recycled several times with only slight loss of activity.     

CO2和环氧乙烷直接制备碳酸乙烯酯的研究进展

本文综述了利用CO₂和环氧乙烷（EO）直接催化合成碳酸乙烯酯（EC）的研究进展,详细讨论了各种催化剂活化EO和CO₂,完成环加成反应的催化机理,并展望了该领域的研究前景。     

A Novel Synthesis of N-Methyl-N-aryl Carbamates from Aromatic Amines and Dimethyl Carbonate Catalyzed by K2CO3／Bu4NBr

A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3) and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.     

A Pd(OAc)2/[mmim]I Catalyst System for Oxidative Carbonylation of Amines to Carbamates, Ureas, and 2-Oxazolidinones

A Pd(OAc)₂/[mmim]I ([mmim]I=1-methyl-3-methylimidazolium iodide) catalyst system was applied to the oxidative carbonylation of aliphatic amines, aromatic amines, and amino alcohols to carbamates, ureas, and 2-oxazolidinones under different conditions. The catalytic turnover frequencies (TOF, moles of amines converted per mole of catalyst per hour) were 12417, 17368, and 4114 h⁻¹ for the production of methyl N-phenyl carbamate, N,N′-diphenyl urea, and 2-benzoxazolinone, respectively.     

同位素示踪研究K2CO3/CH3I促进的碳酸二甲酯直接合成反应

 采用同位素示踪技术,系统地研究了K2CO3/CH3I促进的CO2插入甲醇直接合成碳酸二甲酯(DMC)的反应机理. 结果表明,固体碱碳酸钾催化剂直接参与了DMC的合成过程, DMC分子中的羰基由CO2插入甲醇后形成,两个甲基分别来源于甲醇和碘甲烷. 本文将以往文献中提出的DMC生成机理和二甲醚生成机理结合起来,并对其进行适当补充后,可以很好地解释实验结果.     

Synthesis and antimicrobial activity of some novel 2-(substituted fluorobenzoylimino)-3-(substituted fluorophenyl)-4-methyl-1,3-thiazolines

The synthesis of several 2-(substituted fluorobenzoylimino)-3-(substituted fluorophenyl)-4-methyl-1,3-thiazolines (2a-t) was carried out by base-catalyzed cyclization of corresponding 1-(fluorobenzoyl)-3-(fluorophenyl)thioureas (1a-t) with 2-bromoacetone in aqueous medium. The structures of the synthesized compounds were confirmed by spectral and elemental analysis. All synthesized compounds were evaluated for in vitro antibacterial activity using Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The minimum inhibitory concentration (MIC) was determined for the most active compounds. In vitro antifungal activity was also determined against the five fungal species (Rhizopus oryzae, Fusarium oxysporum, Aspergillus terreus, A. niger and A. fumigatus).     

Cu/NiO-MoO3/SiO2光催化CO2与CH3OH合成碳酸二甲酯的反应性能

 采用表面改性法制备了MoO3-SiO2复合氧化物,用等体积浸渍法制备了Cu/NiO-MoO3/SiO2光催化剂,并用XRD, Raman, IR, TPD-MS, UV-Vis DRS和光促表面反应研究了催化剂的结构、化学吸附性能、吸光性能和光促CO2与CH3OH合成碳酸二甲酯(DMC)的反应性能. 结果表明, Cu和NiO的引入提高了MoO3在SiO2表面的分散度,且Cu和NiO在MoO3-SiO2表面分散均匀; 在金属Cu位和Lewis酸位Mo6+(或Ni2+)的协同作用下, CO2在催化剂表面形成活性较高的的卧式吸附态, CH3OH在催化剂表面形成分子吸附态和解离吸附态; NiO与MoO3复合后部分形成了 Mo-O-Ni 键联,提高了对光的吸收强度; 金属Cu的负载扩展了材料在可见光范围的吸收; 与热表面催化相比,光催化反应在较低的温度下就能显著进行,并提高了CH3OH的转化率,在110 ℃常压和空速300 h-1的条件下,CH3OH转化率可达13.9%,DMC选择性可达90.1%.     

Synthesis of spiroindene-1,3-dione isothiazolines via a cascade michael/1,3-dipolar cycloaddition reaction of 1,3,4-oxathiazol-2-one and 2-arylidene-1,3-indandiones

The reaction of 1,3,4-oxathiazol-2-one derivative with 2-arylidene-1,3-indandione to furnish novel spiroindene-1,3-dione isothiazoline derivatives by Michael/1,3-dipolar [3+2]-cycloaddition reaction was investigated. The key 1,3-dipolar cycloaddition reaction step was examined in toluene solvent at reflux temperature to obtain mixture of two regioisomers (6a and 6b – 14a and 14b) and single isomers (15–20). The scope of this new reaction was demonstrated with many examples with high reactivity and yields.     

Regioselective 1,3-Dipolar Cycloaddition Reactions of Unsymmetrical Münchnones (1,3-Oxazolium-5-olates) with 2- and 3-Nitroindoles. A New Synthesis of Pyrrolo[3,4-b]indoles

The unsymmetrical mesoionic münchnones 13 (3-benzyl-2-methyl-4-phenyl-1,3-oxazolium-5-olate) and 14 (3-benzyl-4-methyl-2-phenyl-1,3-oxazolium-5-olate) react with the N-protected 2- and 3-nitroindoles 1 (ethyl 2-nitroindole-1-carboxylate), 6 (3-nitro-1-(phenylsulfonyl)indole), and 17 (ethyl 3-nitroindole-1-carboxylate) in refluxing THF to afford in good to excellent yields the pyrrolo[3,4-b]indoles 15 (2-benzyl-1-methyl-3-phenyl-4-carboethoxy-2,4-dihydropyrrolo[3,4-b]indole), 16 (2-benzyl-3-methyl-1-phenyl-4-carboethoxy-2,4-dihydropyrrolo[3,4-b]indole), 18 (2-benzyl-1-methyl-3-phenyl-4-(phenylsulfonyl)-2,4-dihydropyrrolo[3,4-b]indole), and 19 (2-benzyl-3-methyl-1-phenyl-4-(phenylsulfonyl)-2,4-dihydropyrrolo[3,4-b]indole). In several cases the regiochemistry, which is opposite to that predicted by FMO theory, is very high and leads essentially to a single pyrrolo[3,4-b]indole; e.g., 6+13→19 in 74% yield.     

Atom-economy Synthesis of N-Substituted Carbamate from Urea Derivative and Dimethyl Carbonate Catalyzed by La/SiO_2: Characterization and Activity

A series of silica gel immobilized lanthanum catalysts were prepared for the atom‐economy synthesis of N‐substituted carbamates from urea derivatives and dimethyl carbonate. The La/SiO₂ catalysts with lanthanum loadings varied from 1.3 wt% to 8.5 wt% were characterized by AES, BET, XRD, TEM, FT‐IR, XPS and TPD. According to the characterization, lanthanum species with particle sizes of 5–10 nm on the surface of silica gel were formed. The catalysts were all amorphous and the surface areas were 336.5–530.2 m²/g. NH₃‐TPD analysis showed that all samples exhibited similar acid strength with different acid amounts. FT‐IR measurement indicated that the component of lanthanum species on the catalyst surface were La(OH)₃, LaOOH and hydrated La₂O₃. Also, the peak value of the absolute amount of LaOOH was obtained with 4.3 wt% lanthanum loading. The BET surface area decreased dramatically when the lanthanum loading was above 4.3 wt%. In consideration of the results obtained from the catalytic reactions, it could be concluded that LaOOH was the possible active species and high surface area was important for the high catalytic activity.     

K2O助剂对合成碳酸二甲酯用Cu/Ni/ZrO2-SiO2催化剂的吸附和催化性能的影响

 用等体积浸渍法制备了ZrO2－SiO2（ZrSiO）表面复合氧化物负载的Cu－Ni催化剂,并用IR,TPR,TPD及微反技术考察了K2O助剂对CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上的吸附及合成碳酸二甲酯（DMC）反应性能的影响．结果表明：加入K2O助剂使CO2在催化剂表面上的吸附增强,当n（K）／n（Cu＋Ni）＝15％时,CO2在催化剂表面上吸附后生成K2CO3;CH3OH在催化剂表面上的解离吸附态（CH3O－和H＋）的吸附减弱;CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上反应的主要产物为DMC,H2O,CO和CH2O;随着K2O助剂的加入,反应转化率及DMC选择性提高,副产物（CO和CH2O）的选择性下降．根据实验结果,探讨了K2O对催化剂表面活性中心电荷分布的影响．     

Vinyl ether end‐groups in poly(ethylene glycol)s from the Na2CO3‐promoted degradation of 1,3‐dioxolan‐2‐one polymers

The Na₂CO₃‐promoted polymerization of 1,3‐dioxolan‐2‐one (I) to afford poly(ethylene glycol) III was reinvestigated. The reaction appeared to involve a nucleophilic attack against the carbonyl and methylene groups of I to afford poly(carbonate) II with poly(ethylene glycol) linkages and ethylene oxide IV as a side product (10–22%). As the reaction progressed, poly(carbonate) II decreased and poly(ethylene glycol) III increased. Under some conditions, poly(ethylene glycol)s V and VI with vinyl ether terminal groups were formed unexpectedly. The formation of unsaturated products during the polymerization of I/EO (ethylene oxide) has not been reported in the literature. We believe that vinyl ethers were formed from the degradation of poly(carbonate)s and were accompanied by a reduction in molecular weight. The structures of vinyl ethers V and VI were confirmed by hydrogenation of the double bond into the ethyl ether group in VII and VIII, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 152–160, 2000     

负载型Sn2(OMe)4/SiO2催化剂的制备及其催化CO2和CH3OH直接合成碳酸二甲酯的性能

 采用表面改性法制备了负载型Sn2（OMe）4／SiO2双核桥联配合物催化剂，用IR，TPD和微反技术对催化剂的表面结构、化学吸附性质和催化活性进行了研究．结果表明，双核桥联Sn2（OMe）4／SiO2配合物中存在Sn－O－Si双齿配位形式，甲氧基以桥基形式联结两个Sn4＋离子；CO2在催化剂表面以桥式吸附态和甲氧碳酸酯基吸附态存在，而CH3OH只以分子吸附态存在．在反应温度413K，压力0．5MPa，反应空速1500h－1以及CH3OH与CO2的摩尔比为2～2．5的反应条件下，CO2和CH3OH在Sn2（OMe）4／SiO2催化剂上生成碳酸二甲酯的选择性达到近100％．根据实验结果，提出了CO2与CH3OH在Sn2（OMe）4／SiO2催化剂表面上的反应机理，反应物分子共吸附于催化剂表面同一活性位上及CO2的甲氧碳酸酯基吸附态的形成是反应顺利进行的关键因素．     

Synthesis and stereochemistry of new 1,3-thiazolidine systems based on 2-amino-2-(mercaptomethyl)propane-1,3-diol: 4,4-bis(hydroxymethyl)-1,3-thiazolidines and c-5-hydroxymethyl-3-oxa-7-thia-r-1-azabicyclo[3.3.0]octanes

The thiaminalisation of 2-amino-2-(mercaptomethyl)propane-1,3-diol [‘2-(hydroxymethyl)cysteinol’] with aryl(di)aldehydes is reported. The resulting new class of 2-aryl-4,4-bis(hydroxymethyl)-1,3-thiazolidines is investigated by NMR and IR spectroscopy in tandem with DFT calculations, permitting structural assignments that are discussed in terms of conformational analysis, anomeric effects and ring-chain tautomerism. These acquired data are subsequently exploited. After treatment with formaldehyde, the subsequent (double) regio- and diastereoselective oxaminalisation of the 1,3-thiazolidine building-block affords the first non-symmetric series of a thiazolidin-oxazolidine fused system singly functionalised at the C-5 position. An unexpected rearrangement, which consists of the partial relocation of the Ar ligand from the 1,3-thiazolidine to the 1,3-oxazolidine ring, is observed as a major influence on the substitution of the Ar ring. The first single crystal X-ray analysis of the title bicyclic system, which discloses the homo- and/or heterochiral non-bonding interactions, is also presented.     

PdCl2-CuCl2/Li-Al-O对CO低压气相合成碳酸二乙酯反应的催化性能

采用Li NO3对γ-Al2O3进行改性,制备了以多孔锂铝尖晶石为载体,以Pd为活性组分的PdCl2-CuCl2/Li-Al-O负载型催化剂,并考察了催化剂对CO低压气相合成碳酸二乙酯(DEC)反应的催化性能,探讨了载体Li/Al比、改性浸渍方法、不同改性金属、Pd负载量和反应压力等因素对催化剂催化性能的影响.结果表明,当n(Li)/n(Al)=0.2,压力为0.3 MPa和温度为110℃时,DEC的时空收率可达到418 g/(L.h).用Li NO3对γ-Al2O3改性后的催化剂载体表层具有Li Al5O8尖晶石结构,不同Li/Al比的催化剂载体的晶胞参数、晶胞体积略有不同.采用双金属改性的催化剂载体表面由于结晶度较低不能形成"完全尖晶石结构",其催化活性较低.随着催化剂表面活性组分PdCl2含量的增加,可有效提高产物DEC的时空收率;锂铝尖晶石载体表面的酸性较低,有利于提高目标产物DEC的选择性.     

Asymmetric 1,3-dipolar reactions of 3-sulfinylfuran-2(5H)-ones with 11H-dibenzo[b,e]azepine 5-oxide. Synthesis of pyrroloazepines via isoxazoloazepines

The addition of morphanthridine N-oxide (1) to homochiral 3-p-tolylsulfinylfuran-2(5H)-ones (2a and 2b) under mild conditions affords furoisoxazoloazepines (3a and 3b) in high yields and with complete regioselectivity. The π-facial and endo-selectivities are also complete from 2a, which yields anti-3a-endo as the only diastereoisomer, whereas cycloreversion determines that the anti-3b-endo adduct can be almost exclusively isolated from 2b. Proper manipulation of the furoisoxazoloazepines allows the synthesis of the optically pure isoxazoloazepines and pyrroloazepines.     

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.     

Synthesis of Dimethyl Carbonate from CO2 , Methanol, and Epoxides Using Re（CO） 5 Cl/K2 CO3 as Catalyst System

IntroductionOver the past few years, dimethyl carbonate(DMC) has been proven to be an efficientmethylating,methoxylating, and methoxycarbonylating agent inorganic syntheses, in which DMC is used to replace thetoxic methyl halides, dimethyl sulfate or carb     

CO2和CH3OH直接合成碳酸二甲酯用Cu-Ni/ZrO2-SiO2催化剂

 采用表面反应改性法制备了ZrO2－SiO2（ZrSiO）表面复合物,用等体积浸渍法制备了ZrSiO担载的Cu－Ni双金属催化剂,并用IR,TPD,TPSR和微反技术考察了CO2和CH3OH在催化剂表面上的化学吸附及反应性能．实验结果表明：在Cu－Ni／ZrSiO催化剂上存在着Cu－Ni金属位M,Lewis酸位Zrn＋和Lewis碱位Zr－O－三类活性中心;CO2在金属位和Lewis酸位的协同作用下可形成CO2卧式吸附态,此吸附态在142℃左右可解离成M－CO和Zr－O－;CH3OH在Lewis酸位和Lewis碱位的协同作用下可形成解离吸附态Zr－OCH3和Zr－OH;CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上的主要反应产物为碳酸二甲酯（选择性在85％以上）,另有少量的CH2O,CO和H2O．     

Cu/NiO-V2O5/SiO2催化剂光催化CO2和甲醇合成碳酸二甲酯的研究

采用表面改性法和等体积浸渍法制备了NiO-V₂O₅/SiO₂和Cu/NiO-V₂O₅/SiO₂光催化剂. 用TPR, XRD, UV-Vis DRS, IR和TPD-MS技术对催化剂的结构、吸光性能和化学吸附性能进行了表征, 研究了催化剂上CO₂和甲醇光促表面催化反应的反应性能. 结果表明, 半导体NiO和V₂O₅复合后部分形成了Ni^2＋—O—V^5＋键联, 而且NiO和V₂O₅在催化剂表面有相互修饰作用, NiO的加入有助于提高V₂O₅在载体SiO₂表面的分散程度, 抑制V₂O₅的聚集, 而且金属Cu和NiO的引入扩展了催化剂的光响应范围. 在催化剂表面存在多种活性吸附位, 催化剂对CO₂和甲醇的有效吸附使得其在较低温度下就能促进碳酸二甲酯的紫外光化学合成. 用Cu/NiO-V₂O₅/SiO₂催化剂, 在常压、空速300 h^－1、140 ℃和125 W紫外灯辐照的情况下, CH₃OH的转化率为14.2%, 碳酸二甲酯的选择性可达89.9 %.