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1.
ZnO is an effective heterogeneous catalyst for the reaction between arylcyanamides with sodium azide to synthesize the arylaminotetrazoles in good yields. This method has advantages of good yields, simple methodology, short reaction times, and easy workup. Furthermore, the catalyst can subsequently be reused for several times without any significant loss of activity.  相似文献   

2.
Marko Anderluh   《Tetrahedron letters》2006,47(52):9203-9206
The current synthesis of hybrid morpholino-glycoamino acids through double reductive amination is characterized by modest yields and lengthy reaction times. We propose an optimized procedure that results in improved yields and the shortest reaction times reported so far.  相似文献   

3.
The oxidative decarboxylation of various ??-aryl- and ??,??-arylcarboxylic acids having electron-donating and electron-withdrawing groups by using a stoichiometric amount of potassium 12-tungstocobaltate(III), K5CoIIIW12O40, in 50% aqueous acetonitrile solution resulted in the corresponding aldehydes and ketones in high yields within short reaction times under microwave irradiation. This transformation was also carried out under the conventional heating conditions which produced the corresponding aldehydes and ketones in relatively longer reaction times. The arylacetic acids with electron-withdrawing substituents required longer reaction times and produced lower yields. In contrast to arylacetic esters which were inert toward decarboxylation, the sodium arylacetates were decarboxylated in shorter times with yields better than those of the parent acids.  相似文献   

4.
Thioacids and thioamino acids were synthesized in excellent yields from readily available acyl benzotriazoles and sodium hydrosulfide in water at room temperature. The new methodology features mild reaction conditions, high yields, short reaction times, and does not involve the use of organic solvents or bases. The reaction is eco-friendly, and the workup procedure is simple and does not require chromatographic separation.  相似文献   

5.
Viologens are generally synthesized by N-alkylating 4,4′-bipyridine with alkyl halides. Under conventional heating conditions, however, their synthesis suffers from long reaction times and, often, low yields. In this work, symmetric and asymmetric viologens were synthesized under the assistance of microwave irradiation in good to excellent yields and in short reaction times.  相似文献   

6.
Olefinic benzyl ethers react with aryltellurium trichlorides leading to tetrahydrofurans in high yields. The reaction times and yields are similar to the analogous cyclization of the corresponding olefinic alcohols. The stereoselec-tivity of the transformation is low.  相似文献   

7.
Magnesium perchlorate has been found to be an efficient catalyst for the synthesis of imines and phenylhydrazones by the reaction of carbonyl compounds with amines and phenylhydrazine in high yields at room temperatures and in short times. The condensation of less electrophilic carbonyl compounds with poorly nucleophilic amines affords the imines in excellent yields.  相似文献   

8.
1,2-Ethylenebis(triphenylphosphonium)chlorochromate was quantitatively prepared and used for the oxidation of various benzylic and some aliphatic alcohols to their corresponding carbonyl compounds in water or acetonitrile and under microwave irradiation. This new oxidizing agent has advantages over similar oxidants in terms of the amount of used oxidant, short reaction time, simple work-up, and high yields. Furthermore, the oxidation of alcohols occurred under microwave irradiation many times and it produced the corresponding carbonyl compounds with high yields and short reaction times, when compared with the conventional method. Finally, the oxidation of different alcohols were accomplished in water under reflux condition with good yields as green chemistry.  相似文献   

9.
Polystyrene‐supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid effectively activates hexamethyldisilazane (HMDS) for the efficient silylation of alcohols and phenols at room temperature. In this heterogeneous catalytic system, primary, secondary, and tertiary alcohols as well as phenols were converted to their corresponding trimethylsilyl ethers with short reaction times and high yields under mild reaction conditions. The heterogenized catalyst is of high reusability and stability in the silylation reactions and was recovered several times with negligible loss in its activity or a negligible catalyst leaching, and also there is no need for regeneration. It is noteworthy that this method can be used for chemoselective silylation of different alcohols and phenols with high yields.  相似文献   

10.
The Ugi reaction goes fast with high yields in a recyclable and biodegradable low-melting mixture of choline chloride and urea (DES) as a novel and efficient reaction medium. The DES is applicable to a wide range of aldehydes, amines, isocyanides, and acids in good to excellent isolated yields (60–92%) and short reaction times (2–5 h) and can be reused four times without any loss of activity.  相似文献   

11.
The synthesis and characterization of Zr-MCM-41 nanoreactors and their catalytic activity in the synthesis of new amino nitrile derivatives by the Strecker reaction in high yields and in short reaction times is reported.  相似文献   

12.
Rapid and efficient preparation of 2-imidazolines and bis-imidazolines by reaction of ethylenediamine with nitriles in the presence of catalytic amounts of sulfur under ultrasonic irradiation is reported. The advantages of this system are short reaction times, high yields and the ability to carry out large scale reactions.  相似文献   

13.
A simple and efficient one‐pot method is described for the synthesis of phosphoramidates/phosphates in excellent yields from dialkylphosphites and trichloroisocyanuric acid in acetonitrile and subsequent treatment with dialkyl amines/alcohols. The procedure is operationally simple, has reduced reaction times, and uses a one‐pot procedure.  相似文献   

14.
Poly(ethylene oxide) (PEO)/methanol can be used as solvent medium for the Pd-catalyzed Suzuki cross-coupling reaction under mild conditions. After the end of the reaction the product is extracted with heptane and the polar phase can be reused several times without any change in the activity. Pure biaryl products are obtained from the nonpolar phase in excellent isolated yields (>90%). The same catalyst-containing polar phase was used to coupling different aryl halides furnishing the biaryl products in good to high isolated yields.  相似文献   

15.
Ultrasound-assisted green syntheses of novel potentially bioactive pyrimidine derivatives have been carried out. The same compounds were obtained by conventional methods of synthesis, and the reaction times and yields of final products obtained by these two methods were compared. It was found that the time of utrasound-promoted reactions was reduced by almost 6–96 times, and their yields were equal or turn out to be greater compared to the traditional approach. The synthesized compounds showed a pronounced stimulating effect on plant growth. The most active derivatives were selected for deeper biological studies and subsequent field trials.  相似文献   

16.
The quantum yields and decay times of bromo-substituted perylenes are nearly identical with those of perylene. The lack of an expected internal heavy atom effect is due to the absence of a triplet energetically close to the fluorescing state.  相似文献   

17.
Shapi A. Siddiqui 《Tetrahedron》2005,61(14):3539-3546
An improved and rapid one-pot synthesis of 2,4,5-triaryl imidazoles in a room temperature ionic liquid is described, which does not need any added catalyst. Different ionic liquids based on 1-n-butyl and 1,3-di-n-butyl imidazolium salts were screened and their efficacy in terms of acidity and polarity have been correlated with yields and reaction period. The one-pot methodology resulting in excellent isolated yields in short reaction times is characterized by simple work up procedures and efficient recovery and recycling of the ionic liquid, which acts as a promoter.  相似文献   

18.
One-pot condensation/oxidation of aldehydes and primary anilines into nitrones using graphite oxide (GO) and Oxone as the oxidant under very mild reaction conditions is described. The proposed method provides a direct oxidative synthesis of various nitrones in good to excellent yields under metal-free conditions in short reaction times.  相似文献   

19.
A convenient, mild and cost‐effective synthesis of palladium nanoparticles stabilized by a mixture of natural carbohydrate beads (gum arabic and pectin) as a new bio‐organometallic catalyst is reported. Powder X‐ray diffraction, transmission and scanning electron microscopies and energy‐dispersive X‐ray and UV–visible spectroscopies were employed to characterize this supported Pd nanoparticles/gum arabic/pectin catalyst. The nanocatalyst exhibited efficient activity in Mizoroki–Heck cross‐coupling reactions between various aryl halides and n ‐butyl acrylate under solvent‐free conditions. The catalyst can easily be recovered from the reaction system and reused several times with high yields. The products were obtained in short reaction times with excellent yields.  相似文献   

20.
A direct synthesis of substituted xanthenes from salicylaldehydes and cyclohexenones or tetralones has been developed. The reaction is catalysed by Lewis acids like scandium triflate and furnishes substituted xanthenes in good to excellent yields using either microwave or thermal heating. Microwave heating results in significantly shortened reaction times of 30 min and generally higher yields.  相似文献   

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