Nanocrystalline magnesium oxide: a novel and efficient catalyst for facile synthesis of 2,4,5-trisubstituted imidazole derivatives

Abstract  

Nanocrystalline magnesium oxide with high specific surface area has been used as a novel and efficient catalyst for an improved and rapid synthesis of biologically active 2,4,5-trisubstituted imidazoles, by three-component, one-pot condensation of 1,2-diketones and aryl aldehydes, in excellent yields under solvent-free and conventional heating conditions. The method has several advantages, for example excellent yields, shorter reaction time, and use of a non-toxic and recyclable catalyst.     

One pot synthesis of aminonaphthoquinone derivatives using Cu(II) immobilized on hyperbranched polyglycerol functionalized graphene oxide as a reusable catalyst under solvent-free conditions

A new Cu(II) immobilized on hyperbranched polyglycerol (HPG) functionalized graphene oxide catalyst was prepared and characterized by FT-IR, TGA, FE-SEM, XRD, and ICP-OES techniques. This catalyst was used efficiently for the preparation of aminonaphthoquinones via one-pot three-component condensation reaction under solvent-free conditions. The catalyst could be easily recovered and reusable several times without a significant loss of activity, which make this method attractive and in a close agreement with green chemistry.     

Synthesis of jasminaldehyde using magnesium organo silicate as a solid base catalyst

Synthetic talc (magnesium organo silicates; MOS) was synthesized by sol–gel method under non-hydrothermal conditions and modified by introducing amine/diamine functionalities in the interlayer space. The applicability of amine/diamine functionalized MOS was studied as catalysts for the synthesis of jasminaldehyde or -pentylcinnamaldehyde by condensation of 1-heptanal with benzaldehyde. The effect of amine/diamine functionality, amount of catalyst, benzaldehyde to 1-heptanal molar ratio and temperature on the selectivity of jasminaldehyde was studied in detail. The highest conversion of 1-heptanal (99%) with 82% selectivity of jasminaldehyde was achieved using MOS3 as a catalyst. The rate constant for condensation of 1-heptanal with benzaldehyde was calculated under optimized reaction conditions. This is the first report on application of MOS as a solid base catalyst for the condensation of 1-heptanal with benzaldehyde.     

Nanocrystalline cobalt oxide: a catalyst for selective alkane oxidation under ambient conditions

Nanocrystalline cobalt oxide activates propane, yielding propene at room temperature and pressure.     

Sulfated polyborate: An efficient and reusable catalyst for one pot synthesis of Hantzsch 1,4-dihydropyridines derivatives using ammonium carbonate under solvent free conditions

A simple and efficient method for the synthesis of four-component 1,4-dihydropyridines of various aldehydes, β-ketoesters and ammonium carbonate catalyzed by sulfated polyborate with high yields under a solvent free condition at 90 °C is described. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup, recyclability of catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards.     

Nanosized magnesium oxide as a highly effective heterogeneous base catalyst for the rapid synthesis of pyranopyrazoles via a tandem four-component reaction

A four-component reaction of hydrazine hydrate or phenyl hydrazine, ethyl 3-alkyl-3-oxo propanoate, aldehydes and malononitrile has been achieved in the presence of nanosized magnesium oxide as a highly effective heterogeneous base catalyst to produce of 6-amino-3-alkyl-4-aryl-5-cyano-1,4-dihydropyrano[2,3-c]pyrazole derivatives in excellent yields and in a short experimental time. This method is simple and rapid for focusing a pyrano ring with a pyrazole ring.     

NBS as an efficient catalyst for the synthesis of 1,5-benzodiazepine derivatives under mild conditions

Various biologically important 1,5-benzodiazepine derivatives were efficiently synthesized in excellent yields using catalytic amounts of NBS (10 mol %). This inexpensive, nontoxic, and readily available catalyst efficiently catalyzes the condensation of several aromatic as well as aliphatic ketones with substituted o-phenylenediamines.     

Room temperature ionic liquid promoted synthesis of 1,5-benzodiazepine derivatives under ambient conditions

The reaction of o-phenylenediamines with both acyclic and cyclic ketones in the ionic liquid 1,3-di-n-butylimidazolium bromide afforded 1,5-benzodiazepines in excellent isolated yields in the absence of a catalyst at ambient temperature.     

A convenient and mild one pot synthesis of cyclopentenone derivatives

Developed a convenient and mild one pot synthesis of cyclopentenone derivatives using 1-acetyl-1-cyclohexene and wide range of aldehydes. Aromatic and heterocyclic aldehydes with electron donating and withdrawing groups were conveniently converted to the corresponding cyclopentenone derivatives.     

Zeolite ZSM-11 as a reusable and efficient catalyst promoted improved protocol for synthesis of 2,4,5-triarylimidazole derivatives under solvent-free condition

Research on Chemical Intermediates - Zeolite ZSM-11 catalyst was prepared by hydrothermal method and characterized by FTIR, XRD, SEM, HRTEM, EDS, and BET analysis techniques. The catalyst shows...     

An efficient one‐pot synthesis of polyhydrobenzoacridine‐1‐one derivatives under microwave irradiation without catalyst

A series of 3,3‐dimethyl‐9‐substituted‐1,2,3,4,9,10‐hexahydrobenzo[c] acridine‐1‐ones and 3,3‐dimethyl‐9‐substituted‐1,2,3,4,9,10‐hexahydrobenzo[a] acridine‐1‐ones were synthesized by the reaction of an aldehyde, α‐naphthylamine or β‐naphthylamine and dimedone under microwave irradiation with short times and high yields.     

One-pot,three-component synthesis of spiroindoloquinazoline derivatives under solvent-free conditions using ammonium acetate as a dual activating catalyst

The one-pot, three-component synthesis of spiroindoloquinazoline derivatives in good to excellent yields via the condensation reaction of tryptanthrin, CH activated carbonyl compounds and malononitrile under solvent-free conditions in the presence of ammonium acetate is reported.     

焙烧温度对含Mg助剂的铁基催化剂F-T合成反应性能的影响

采用连续共沉淀和喷雾干燥技术相结合的方法制备了Mg助剂的Fe/Cu/K/SiO2催化剂,采用N2物理吸附、XRD、MES 和H2-TPR等表征手段,考察了焙烧温度对催化剂比表面积、体相结构和还原性能的影响。结果表明,随着焙烧温度的升高,催化剂的比表面积降低,平均孔径增大,体相中α-Fe2O3晶粒逐渐增大,催化剂变的越来越难还原,其结构更加稳定。在H2/CO （摩尔比）= 2.2、250 ℃、2.0 MPa和2 000 h－1于固定床反应器考察了焙烧温度对该催化剂F-T合成反应性能的影响,结果表明,随着焙烧温度的升高,催化剂的F-T合成反应活性降低,在运行过程中反应活性逐渐增加直至达到平稳,但达到平稳所需的诱导期越来越长;提高焙烧温度使烃产物分布向重质烃方向转移,有利于降低CH4的选择性,促进重质烃的生成。     

Fe-Ca磁性固体碱催化剂上菜籽油酯交换反应

采用原位沉淀法合成了双功能磁性固体碱催化剂CaO·γ-Fe₂O₃,用于催化菜籽油酯交换反应制备生物柴油。利用XRD、BET、TG-DTA、SEM和VSM对催化剂进行了表征,用ICP-AES对产物脂肪酸甲酯(FAME)中Ca、Fe残留量进行了测定。结果表明,Fe和Ca两种组分间有较好复合,催化剂显示出较好的磁学性能,饱和磁化率达到45.7emu/g,明显高于文献报道的磁性碱催化剂。在温和的反应条件(常压、64℃、催化剂加入量为油重的2.5%、醇油摩尔比15、转速750r/min)下,反应2h,重复使用前三次酯交换反应转化率都维持在95%左右。     

Selectfluor promoted environmental-friendly synthesis of 2H-chromen-2-ones derivatives under various reaction conditions

A simple, clean and benign route to the synthesis of 2H-chromen-2-ones derivatives through one-pot condensation of ??-ketoesters and substituted phenols in the presence of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborateis (Selectfluor? F-TEDA-BF₄) as catalyst under solvent free reaction conditions was experimented. The application of ultrasonic irradiation improved the yields and reduced the reaction times. The use of selectfluor catalyst is feasible because of its stability, commercial value, easy handling, easy recovery and good activity. To extend our research, the ability of selectfluor for the synthesis of 2-aminochromene derivatives was also examined.     

An efficient one‐pot synthesis of novel pyrimidoquinoline derivatives under microwave irradiation without catalyst

A series of pyrimidoquinoline derivatives were synthesized through one‐pot condensation of 2,6‐diaminopyrimidin‐4‐one, aldehyde and cyclic a 1,3‐dicarbonyl compound in glycol under microwave irradiation without catalyst. The protocol in the absence of catalyst has the advantage of good yield (87‐95%), short reaction time (4‐7 min) and an environmentally friendly technique.     

Selectfluor mediated one pot synthesis of cyclohexanone ring fused isoxazole derivatives

A Selectfluor and base mediated protocol for the synthesis of cyclohexanone ring fused isoxazole derivatives from isoxazoline N-oxides has been successfully developed. This rapid, one-pot, two-step transformation is achieved in acetonitrile, through nitroso intermediate followed by hydration, defluorination and N–O coupling in the presence of triethylamine. The scope and mechanism of the protocol have been demonstrated.