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排序方式: 共有134条查询结果,搜索用时 343 毫秒
31.
A simple and efficient procedure for reductive methylation of primary and secondary amines using N‐methylpiperidine zinc borohydride (ZBNMPP), giving tertiary amines, is described. The reaction is carried out in methanol at room temperature under neutral conditions. 相似文献
32.
In this paper we give a classification of special endomorphisms of nil-manifolds:Let f:N/Γ → N/Γ be a covering map of a nil-manifold and denote by A:N/Γ → N/Γ the nil-endomorphism which is homotopic to f. If f is a special T A-map, then A is a hyperbolic nil-endomorphism and f is topologically conjugate to A. 相似文献
33.
The ethylenebis(N‐methylimidazolium) chlorochromate was prepared by addition of N‐methylimidazole to 1,2‐dibromoethane to form the corresponding dibromide salt and subsequent treatment of this salt with CrO3 in 6N HCl solution. It is a stable yellow‐orange solid which selectively oxidized benzylic and allylic alcohols, hydroquinones and trimethylsilyl ethers in refluxing acetonitrile. Oxidation of alcohols was also examined under solvent‐free conditions and showed much better yields of the corresponding carbonyls in a very short reaction time when compared with the conventional method. 相似文献
34.
Heshmatollah Alinezhad Mahmood Tajbakhsh Mahboobeh Zare Mahboobeh Mousavi 《Heteroatom Chemistry》2016,27(5):290-294
Phenylphosphinic acid is found to catalyze the three‐component condensation of an aldehyde, enaminone, and urea or thiourea to afford the corresponding 6‐unsubstituted dihydropyrimidinones in high to excellent yields. This methodology is simple and fast synthetic route for the preparation of interesting class of heterocycles. 相似文献
35.
Mehdi Moemeni Hamid Arvinnezhad Saadi Samadi Mahmood Tajbakhsh Khosrow Jadidi Hamid Reza Khavasi 《Journal of heterocyclic chemistry》2012,49(1):190-194
New spiro[indeno[1,2‐b]quinoxaline‐11,2′‐pyrrolidine] derivatives were prepared in high yield stereoselectively from an efficient multicomponent 1,3‐dipolar cycloaddition reaction between ninhydrin, phenylenediamine, sarcosine, and chalcones. The regiochemistry and stereochemistry of resultant cycloadducts have been determined by several 2D NMR spectroscopic techniques and X‐ray single crystal diffraction. J. Heterocyclic Chem., (2012). 相似文献
36.
Hamid Reza Shaterian Majid Ghashang Manijeh Asadi Nassrin Tajbakhsh Riki 《Journal of the Iranian Chemical Society》2012,9(1):1-5
An efficient green protocol for the synthesis of 1-amidoalkyl-2-naphthols using a three-component, one-pot condensation reaction of 2-naphthol, aromatic aldehyde and amides in the presence of Al(HSO4)3 as heterogeneous catalyst under thermal solvent-free conditions has been described. The present procedure offers advantages such as shorter reaction times, simple work-up procedure, excellent yields, recovery and reusability of catalyst. 相似文献
37.
Rahman Hosseinzadeh Mahmood Tajbakhsh Maryam Mohadjerani Zahra Lasemi 《Monatshefte für Chemie / Chemical Monthly》2009,42(12):57-60
Abstract
Ethylenebis(N-methylimidazolium) ditribromide, a stable crystalline solid, is easily prepared by reaction of the corresponding dibromide salt with bromine in n-hexane. 1,3-Diketones and β-ketoesters can be brominated chemoselectively to the corresponding α-monobrominated products by using this reagent at 0–5 °C. Under the same reaction conditions, diethyl malonate, ethyl cyanoacetate, and malonitrile were monobrominated at moderate yield. 相似文献38.
Setareh Habibzadeh Ghasem Firouzzadeh Pasha Mahmood Tajbakhsh Nasim Amiri Andi Ehsan Alaee 《中国化学会会志》2019,66(8):934-944
A new solid acid catalyst, consisting of 12‐phosphotungstic heteropoly acid (HPW) supported on graphene oxide/silica nanocomposite (GO@SiO2), has been developed via immobilizing HPW onto an amine‐functionalized GO/SiO2 surface through coordination interaction (GO@SiO2‐HPW). The GO@SiO2‐HPW nanocomposite was characterized by Fourier transform infrared (FT‐IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X‐ray diffraction (XRD). The prepared nanocomposite could be dispersed homogeneously in water and further used as a heterogeneous, reusable, and efficient catalyst for the synthesis of benzimidazoles and benzothiazoles by the reaction of 1,2‐phenelynediamine or 2‐aminothiophenol with different aldehydes. 相似文献
39.
Majid M. Heravi Dariush Ajami Bagher Mohajerani Mahmood Tajbakhsh Mitra Ghassemzadeh Kourosh Tabar-Hydar 《Monatshefte für Chemie / Chemical Monthly》2001,132(7):881-883
Summary. A new, efficient, and environmentally benign method for the cleavage of semicarbazones has been achieved by a simple reaction
of semicarbazones with clayfen under microwave irradiation.
Received January 4, 2001. Accepted (revised) March 1, 2001 相似文献
40.
Polycaprolactone (PCL) is a bioresorbable and biocompatible polymer that has been widely used in long-term implants and controlled drug release applications. However, when it comes to tissue engineering, PCL suffers from some shortcomings such as slow degradation rate, poor mechanical properties, and low cell adhesion. The incorporation of calcium phosphate-based ceramics and bioactive glasses into PCL has yielded a class of hybrid biomaterials with remarkably improved mechanical properties, controllable degradation rates, and enhanced bioactivity that are suitable for bone tissue engineering. This review presents a comprehensive study on recent advances in the fabrication and properties of PCL-based composite scaffolds containing calcium phosphate-based ceramics and bioglasses in terms of porosity, degradation rate, mechanical properties, in vitro and in vivo biocompatibility and bioactivity for bone regeneration applications. The fabrication routes range from traditional methods such as solvent casting and particulate leaching to novel approaches including solid free-form techniques. 相似文献