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61.
Magnetic CuFe2O4 nanoparticles: a retrievable catalyst for oxidative amidation of aldehydes with amine hydrochloride salts 总被引:1,自引:0,他引:1
The application of magnetic CuFe2O4 nanoparticles for the oxidative amidation of aldehydes with amine hydrochloride salts is described. A wide range of amides have been synthesized in good to excellent yields under mild conditions. Chiral amide also synthesized from its corresponding chiral amine salt with retention of the stereochemistry. In particular, the performance of the magnetic separation of the catalyst was very efficient and an alternative to time, solvent and energy-consuming separation procedures. The catalytic activity of the catalyst remains unaltered after five consecutive cycles, making it environmentally benign and widely applicable due to its efficiency, ease of handling and cost effectiveness. 相似文献
62.
63.
Merino I Laxmi Y R S Flórez J Barluenga J Ezquerra J Pedregal C 《The Journal of organic chemistry》2002,67(3):648-655
The reaction between N-alkylidene glycine ester enolates, generated from glycine esters aldimines with LDA in THF at low temperature, and chiral alkoxyalkenylcarbene complexes of chromium provided directly 2,4,5-trisubstituted-3-pyrrolidinylcarbene complexes with total exo selectivity and very high syn and facial diastereoselectivity when carbene complexes bearing the (-)-8-phenylmenthyloxy group were employed. Oxidation of the metal carbene moiety followed by basic hydrolysis of the esters afforded enantiomerically highly enriched syn,exo-3,4,5-trisubstituted prolines, whereas acidic hydrolysis of the same functional groups proceeded with epimerization at the alpha-amino acid center leading to anti,exo-3,4,5-trisubstituted prolines of very high enantiomeric purity as well. 相似文献
64.
D. Srinivasa Yogi G. Narendra Kumar M. Srinivas Mohan Y. Laxmi Kumari 《Journal of Chemical Sciences》1994,104(4):443-451
The formation constants for ternary metal complexes (MLA) where L = ethylenediaminediacetic acid (EDDA), M = Cu(II) and A
= glycine, alanine, leucine, serine, threonine, methionine, proline, phenylalanine, tryptophan, histidine, aspartic acid,
ethylenediamine, histamine, 2,2′-bipyridyl, 1,10-phenanthroline, imidazole, oxalic acid, malonic acid, pyrocatechol and nitropyrocatechol
have been investigated by pH-metric method at 35°C andμ = 0.2 M (KNO3). With respect to the donor atoms on ligand A, the stabilities of the ternary complexes increase in the order O−-O− < N-O−≈N-N. The stabilities of the various ternary complexes decrease with the increasing number of carboxylate groups on the ligand
in the order ethylenediamine (EN) < ethylenediamine monoacetic acid (EDMA) < EDDA. Various factors influencing the formation
and stabilities of ternary complexes are discussed. 相似文献
65.
Manral L Kumar Gupta P Ganesan K Chandra Malhotra R 《Journal of chromatographic science》2008,46(6):551-555
Narcotic analgesics of the fentanyl class are characterized by high potency and relatively short duration of action. These compounds nowadays have become a substitute for heroine and are highly addictive for abusers. Herein, we report retention indices of fentanyl and its eighteen analogues relative to the homologous n-alkane series. These values are determined on a moderately polar BP-5 capillary column under programmed temperature and isothermal chromatographic conditions. The analogues differ in the substituent attached to the piperidine ring nitrogen, and retention indices are found to vary according to the nature of the substituent. The effects of chromatographic conditions like temperature programming rate, carrier gas flow rate, and oven temperature are studied. Retention indices are also determined on a non-polar BP-1 column to study the influence of stationary phase polarity. Standard deviation of all the RI values is less than one index unit. 相似文献
66.
In this paper, we analyse a multi-server queue with bulk arrivals and finite-buffer space. The interarrival and service times
are arbitrarily and exponentially distributed, respectively. The model is discussed with partial and total batch rejections
and the distributions of the numbers of customers in the system at prearrival and arbitrary epochs are obtained. In addition,
blocking probabilities and waiting time analyses of the first, an arbitrary and the last customer of a batch are discussed.
Finally, some numerical results are presented.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
67.
Mithun Rudrapal Ashwini K. Mishra Laxmi Rani Khomendra K. Sarwa James H. Zothantluanga Johra Khan Mehnaz Kamal Santwana Palai Atul R. Bendale Swati G. Talele Vasim T. Pathan Laxmikant B. Borse Vishnu S. Neharkar Pravat K. Sahoo 《Molecules (Basel, Switzerland)》2022,27(24)
Advancement in nanotechnology has unleashed the therapeutic potentials of dietary polyphenols by enhancing bioavailability, improving biological half-life, and allowing site-specific drug delivery. In this review, through citation of relevant literature reports, we discuss the application of nano-pharmaceutical formulations, such as solid lipid nanoparticles, nano-emulsions, nano-crystals, nano-polymersomes, liposomes, ethosomes, phytosomes, and invasomes for dietary polyphenols. Following this, we highlight important studies concerning different combinations of nano formulations with dietary polyphenols (also known as nanophytopolyphenols). We also provide nano-formulation paradigms for enhancing the physicochemical properties of dietary polyphenols. Finally, we highlight the latest patents that were granted on nano-formulations of dietary polyphenols. Based on our review, we observe that nanosized delivery of herbal constituents, spices, and dietary supplements have the ability to improve biological processes and address issues connected with herbal treatments. 相似文献
68.
Sushma Singh Laxmi K. Sharma Apoorv Saraswat Ibadur R. Siddiqui Rana K. Pal Singh 《Research on Chemical Intermediates》2014,40(3):947-960
A convenient, efficient and one-pot synthesis of chemically and pharmaceutically interesting symmetrical-2,5-disubstituted-1,3,4-oxadiazoles is reported. The protocol involves anodic oxidation of aldehyde-N-arylhydrazones in anhyd. MeCN–LiClO4. Constant potential electrolysis carried out in an undivided cell and platinum electrodes leads to the formation of the corresponding oxadiazoles under ambient condition and the mechanism was deduced from voltammetry studies. The reaction proceeded smoothly with high atom economy. 相似文献
69.
A facile three step synthesis of 3-aryl-2,2-dimethyl-cyclopropanecarboxylates, intermediates for pyrethroid acaricides, involving formation of arylidene phenylsulfonylacetate, MIRC reaction of the latter with potassium 2-nitropropane and desulfonylation of the cyclopropane intermediate with sodium amalgam in fair overall yield is described. 相似文献
70.