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排序方式: 共有220条查询结果,搜索用时 78 毫秒
1.
Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes 下载免费PDF全文
Manne Annapurna T. Parsharamulu P. Vishnuvardhan Reddy M. Suresh Pravin R. Likhar Mannepalli Lakshmi Kantam 《应用有机金属化学》2015,29(4):234-239
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
Wipf P Coleman CM Janjic JM Iyer PS Fodor MD Shafer YA Stephenson CR Kendall C Day BW 《Journal of combinatorial chemistry》2005,7(2):322-330
Cascade reactions of internal and terminal alkynes, zirconocene hydrochloride, dimethylzinc, and phosphinoyl imines (prepared in one step from aldehydes and diphenylphosphinoyl amide) lead to allylic phosphinoyl amides after aqueous workup. Microwave acceleration allows the completion of this one-pot reaction sequence in 10 min. These allylic amides can be converted into a variety of derivatives, including carbamates and sulfonamides, or reacted prior to workup with diiodomethane to give novel C-cyclopropylalkylamides. A solution-phase "libraries from libraries" approach was used to generate an intermediate 20-member library which was subsequently expanded to a 100-member library by a series of N-functionalizations. The biological activity was evaluated in an assay for competitive binding to the estrogen receptor (ERalpha), revealing three potent lead compounds of a new structural type. 相似文献
3.
A visible light promoted, photoredox catalysed, green one-pot approach for the alkylation of amine substrates with sp2 carbon has been developed. This eosin Y based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for coupling reaction. The proposed strategy includes simple procedure which can make adduct product with sp2 carbon. This eosin Y based photocatalytic hydrogen-atom transfer strategy may hold great potential for diverse functionalization of a wide range of native CH bonds in an economical and sustainable manner. 相似文献
4.
Pravin M. Vaidya 《Mathematical Programming》1996,73(3):291-341
Let
be a convex set for which there is an oracle with the following property. Given any pointz∈ℝ
n
the oracle returns a “Yes” ifz∈S; whereas ifz∉S then the oracle returns a “No” together with a hyperplane that separatesz fromS. The feasibility problem is the problem of finding a point inS; the convex optimization problem is the problem of minimizing a convex function overS. We present a new algorithm for the feasibility problem. The notion of a volumetric center of a polytope and a related ellipsoid
of maximum volume inscribable in the polytope are central to the algorithm. Our algorithm has a significantly better global
convergence rate and time complexity than the ellipsoid algorithm. The algorithm for the feasibility problem easily adapts
to the convex optimization problem. 相似文献
5.
An efficient, facile, and practical liquid-phase combinatorial synthesis of benzimidazoles under microwave irradiation is described. In the first step of reaction sequence, polymer-bound activated aryl fluoride was condensed with selective primary amines via an ipso-fluoro displacement reaction. Reduction of the polymer-bound nitro group followed by cyclization with isothiocyanates afforded immobilized benzimidazoles. The desired products were obtained in high yield with high purity after detaching from the soluble matrix. All reactions involved (S(N)Ar reaction, reduction, cyclization, and support cleavage) were performed completely within a few minutes under microwave irradiation. The coupling of microwave technology with liquid-phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries. 相似文献
6.
P. Madhavan Bandlamudi Mallikarjuna Rao B. Pravin S. Abhishek P. R. Kumar M. Sreenivasulu K. B. Chandrasekhar 《Chromatographia》2007,66(3-4):243-246
A chiral liquid chromatographic method for enantiomeric resolution of β-amino-β-(3-methoxyphenyl) propionic acid was developed
and validated. The “hybrid” π-electron donor–acceptor based stationary phase (R,R) Whelk-01 was found to be enantiomerically
selective for (R) and (S) enantiomers of β-amino-β-(3-methoxyphenyl) propionic acid with a resolution greater than 2.0. The effects of isopropyl alcohol
and ethanol on enantioselectivity and resolution of enantiomers were evaluated. Calibration curves were linear over the range
of 0.10–1.00, with a regression coefficient (r) of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were 300 and 1,000 ng mL−1 respectively for 10 μL injection volume. The percentage RSD of the peak area of six replicate injections of (S) enantiomer at LOQ concentration was 2.8. The percentage recovery of (S) enantiomer from (R) enantiomer samples ranged from 92 to 102. The test solution was observed to be stable up to 24 h after the preparation.
The developed normal phase chiral LC method can be used for the enantiomeric purity evaluation of R-β-amino-β-(3-methoxyphenyl) propionic acid. 相似文献
7.
A one‐pot, multistep synthesis of acridine‐1,8(2H,5H)‐diones ( 4a–m ) was achieved by three‐component reaction of dimedone ( 1 ) with an aromatic aldehyde ( 2a–m ) and an ammonium acetate ( 3 ) using water as a green solvent without any catalyst and a simple, easily handled, and ultrasonic technique as well as conventional method. 相似文献
8.
A facile, efficient oxidative deblocking of aldoximes and ketoximes to their corresponding aldehydes and ketones have been achieved by using silica gel supported chromium trioxide. 相似文献
9.
The synthesis of a benzooxazol-5-yl acetic acid derivative (9) with strong heparanase and angiogenesis inhibitory activity, and thus possible commercial interest, is described in detail. 相似文献
10.