Highly efficient synthesis of β-amino esters via Mannich-type reaction under solvent-free conditions using ZnCl_2 catalyst

β-Amino esters were synthesized via ZnCl2-catalyzed Mannich-type reaction of imines and malonate esters under solvent-free conditions in 6 min. The β-amino ester was converted into the corresponding aspartic acid derivatives.

A Rapid and Efficient Synthesis of Diaryl Thioureas via Solvent-Free Reaction Using Microwave

A rapid and efficient method for the preparation of diaryl thiourea compounds was reported for the first time. Twelve diaryl thiourea compounds that possessing biological activity have been synthesized in excellent yields (91-97%). The reaction proved to be extremely simple and highly efficient (in 1.5-4.5 min).

Efficient Solvent- and Catalyst-Free Syntheses of Imine Derivatives Applying the Pressure Reduction Technique: Remarkable Change of the Reaction Rate with the Phase Transition

Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.

Facile One-Pot Synthesis of Novel Hexahydro-2-quinolinecarboxylic Acids under Solvent-Free Reaction Conditions

A simple and fastthree-component synthesis of new and biologically active hexahydro-2-quinolinecarboxylic acid scaf-fold 4 was carried out using cyclocondensation reaction of arylmethylidenepyruvic acids 1, 1,3-cyclohexandiones 2 and ammonium acetate 3 under solvent-free conditions and at room temperature. This protocol has the advantages of facility, easy work-up, high yields, short reaction time and environmentally friendly character.

可控微波促进对称1,n-亚甲基二酯的环境友好合成

采用可控微波加热技术,在水作溶剂或无溶剂条件下芳甲酸与1,n-二溴代烷发生双酯化反应,“一锅”法高效地合成了系列亚甲基二羧酸酯类化合物.考察了反应温度、时间、碱、溶剂对双酯化产率的影响,在优化实验条件下合成了31种亚甲基二羧酸酯,底物适用范围广,并提出了合理的反应机理.该方法操作简单、时间短,产率较高,同时符合绿色化学的原则.

Zr-MOF固载聚离子液体对CO_(2)环加成反应的催化性能

通过无溶剂限域封装,将二溴对二甲苯和4,4′-联吡啶吸附至UiO-67材料微孔中,并原位聚合成聚离子液体PBpy-Br,得到兼具Br^(-),Zr-OH/Zr-OH_(2)和N杂环3种活性中心的复合材料PBpy-Br@UiO-67.采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、^(13)C核磁共振波谱(^(13)C NMR)、比表面积分析(BET)和热重分析(TGA)等手段对材料进行了表征,并将其应用于催化CO_(2)与环氧氯丙烷的环加成反应中.在单因素实验基础上,通过响应面优化确定的最佳反应条件为反应温度100℃、p_(CO_(2))=0.1 MPa、催化剂用量(质量分数)0.22%以及反应时间22 h.在该条件下,环氧氯丙烷转化率达99.6%,催化剂循环使用5次后,转化率仅下降2.3%.此外,对PBpy-Br@UiO-67的普适性进行了研究,将其用于催化其它环氧化物与CO_(2)反应,转化率均在50%以上.研究结果表明,PBpy-Br@UiO-67催化剂具有反应条件温和及催化效率高的特点,为CO_(2)的固定与转化提供了新催化体系.

Oxalic acid catalyzed solvent-free one pot synthesis of coumarins

Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.

BF_3·OEt_2 Promoted Solvent-free Synthesis of Benzimidazole Derivatives

Differently substituted benzimidazoles have been synthesized in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of BF3·OEt2 as a catalyst. The method is applicable to aromatic, unsaturated and aliphatic aldehydes and to substituted o-phenylenediamines without significant differences.

Solvent Free One-Pot Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles Catalyzed by Secondary Amine Based Ionic Liquid and Defective Keggin Heteropoly Acid

Secondary amine based ionic liquid and defective Keggin type heteropoly acid (HPA) are separately used for efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles assisted by microwave (MW). Eco-friendly solvent free procedure, short reaction time, high yield of products and reusability of catalysts are important features of the synthesis. A comparative study on the efficiency of the two catalysts is reported. This work further demonstrates the alternate use of urea, instead of often used ammonium acetate, as source of nitrogen.

An efficient and solvent-free one-pot synthesis of dihydropyrimidinones under microwave irradiation

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives using formic acid as catalyst, from aldehydes, β-ketoester and urea(thiourea) without solvent under the irradiation of microwave is described. Compared with the classical Biginelli reaction, this new method has the advantage of good yields (77–94% for aromatic aldehydes) and short reaction time (3–8 min).

Silica triflate as an efficient reagent for the solvent-free synthesis of coumarins

Silica triflate, as a new silica-based reagent, can be used for the efficient synthesis of 4-substituted coumarins via a Pechmann reaction under solvent-free reaction conditions. All reactions were performed at 80 ℃ in good to high yields.

An efficient and green preparation of 5-aminophosphonate substituted pyrimidine nucleosides under solvent-free conditions

An environmentally benign and highly efficient one-pot preparation of α-aminophosphonates under solvent-free conditions was developed. By employing this method, 5-aminophosphonate substituted pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-forrnyl-2＇-deoxyuridine, aniline and dimethylphosphite.

Solvent-free synthesis of some ethyl arylglyoxylates

An efficient and convenient approach to synthesize of ethyl arylglyoxylates by solvent-free grinding was described. Eight ethyl arylglyoxylates had been synthesized by this method, this method provided several advantages such as little pollution, high yield, good selectivity, and simple workup procedure, their structures were confirmed by IR, ^1HNMR.

布洛芬生产工艺中Friedel-Crafts酰化反应的无溶剂连续流工艺设计

针对传统布洛芬生产工艺过程的Friedel-Crafts酰化反应中存在工艺复杂、能耗大、环境压力大的问题,本研究将无溶剂连续流合成技术应用于2-氯丙酰氯与异丁基苯的Friedel-Crafts酰化反应,设计了一个无溶剂连续流反应体系,通过考察停留时间、温度、总流量和物质的量比等因素,优化工艺并获得最佳的生产条件,安全有效地实现了高腐蚀性汽液混合物的连续流合成反应中高质量芳基酮的制备,异丁基苯的转化率和芳基酮的纯度可达99%左右。本研究为药物合成领域的连续流合成工艺与相关Friedel-Crafts酰化反应的同系列研究提供参考依据。

Efficient Solvent-Free Preparation of Imines, and Their Subsequent Oxidation with <i>m</i>-CPBA to Afford Oxaziridines

A simple one-pot procedure for the preparation of imines from the corresponding aldehydes and amines, and their subsequent oxidation reaction with m-CPBA to produce synthetically useful oxaziridines is reported. The method is applicable to imines derived from both aliphatic and aromatic aldehydes and diverse alkyl amines. Short reaction times, essentially quantitative yields, very mild reaction conditions, and easy purification are the main features of the procedure reported herein.

Nonequilibrium Solvent Free Energy Curve from Molecular Theory in Electron Transfer Reaction

The microscopic moleeular theory for electron transfer in a model solvent ishahr developed. The nonlinear response of the solvent molecules is be computedquanitatively in a new way. Adopting computer simulation daa and choosingappropriate reaction coordinae, a reasonable free energy dinram is constructed and thercorganhaion energy for the product state is calculated.

Perfect Solvent- and Catalyst-Free Syntheses of Imine Derivatives Using the Pressure Reduction Technique

In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and catalyst-free syntheses of imines using the pressure reduction technique as a key technology. We found that this reaction proceeded very rapidly in the initial stage, but its rate decreased with the passage of time. It was also found that the reaction of benzaldehyde with aniline had a specificity that the phase transition occurred. In this method, the desired imines could be obtained in good to excellent yields, but target compounds had to be given by purifications using organic solvents. Therefore, we tried to develop the perfect synthetic method of imine derivatives without organic or inorganic solvents. We selected two methods and took them into this investigation. One was exactly mixing (1:1, substance ratio) aldehydes and amines and the other was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the pressure reducing technique. When this improved synthetic method was performed, it was revealed that pure target imines were obtained in excellent yields without any purification.

Ga(ClO_4)_3-catalyzed Reaction of 1,2-Diamines and α-Bromoketones:Synthesis of 2-Substituted Quinoxalines

Ga（ClO4）3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%（molar fraction） catalyst under solvent-free conditions at room temperature.For unsymmetrical o-phenylenediamines bearing electron-withdrawing groups,regio-selective quinoxalines were obtained.

Combined multi-level quantum mechanics theories and molecular mechanics study of water-induced transition state of OH^- + CO_2 reaction in aqueous solution

The presence of a solvent interacting with a system brings about qualitative changes from the corresponding gas-phase reactions. A solvent can not only change the energetics along the reaction pathway, but also radically alter the reaction mechanism. Here, we investigated the water-induced transition state of the OH^-＋CO2→HCO3^- reaction using a multi-level quantum mechanics and molecular mechanics method with an explicit water model. The solvent energy contribution along the reaction pathway has a maximum value which induces the highest energy point on the potential of mean force. The charge transfer from OH^- to CO2 results in the breaking of the OH^- solvation shell and the forming of the CO2 solvation shell. The loss of hydrogen bonds in the OH^- solvation shell without being compensated by the formation of hydrogen bonds in the CO2 solvation shell induces the transition state in the aqueous solution. The calculated free energy reaction barrier at the CCSD（T）/MM level of theory, 11.8 kcal/mol, agrees very well with the experimental value, 12.1 kcal/mol.

One-Pot Four Component Reaction for the Synthesis of Formazans in an Environmentally Benign Procedure Mediated by KHSO₄

A microwave mediated solvent free one pot synthesis of formazans is developed using the solid acid, KHSO4. The products were obtained in a short reaction time in high yield. This study was undertaken to find an alternative and green method for the synthesis of formazans in the absence of corrosive mineral acids, buffered solutions and volatile organic compounds (VOCs).