- An elegant protocol for the synthesis of N-substituted pyrroles through C-N cross coupling/aromatization process using CuFe2O4 nanoparticles as catalyst under ligand-free conditions
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A simple and efficient, ligand-free C-N cross-coupling of aryl halides/benzyl bromides with trans-4-hydroxy-l-proline has been developed to produce aromatized N-substituted pyrroles, using a catalytic amount of magnetically separable and recyclable CuFe2O4 nanoparticles, in the presence of Cs2CO3 in DMSO at 100 °C.
- Satish,Reddy, K. Harsha Vardhan,Ramesh,Kumar, B.S.P. Anil,Nageswar
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supporting information
p. 2596 - 2599
(2014/05/06)
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- Organic synthesis via magnetic attraction: Benign and sustainable protocols using magnetic nanoferrites
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Magnetic nano-catalysts have been prepared using simple modification of iron ferrites. The nm size range of these particles facilitates the catalysis process, as an increased surface area is available for the reaction; the easy separation of the catalysts by an external magnet and their recovery and reuse are additional beneficial attributes. Glutathione bearing nano-ferrites have been used as organocatalysts for the Paal-Knorr reaction and homocoupling of boronic acids. Nanoferrites, post-synthetically modified by ligands, were used to immobilize nanometals (Cu, Pd, Ru, etc.) which enabled the development of efficient, sustainable and green procedures for azide-alkynes-cycloaddition (AAC) reactions, C-S coupling, O-allylation of phenol, Heck-type reactions and hydration of nitriles.
- Nasir Baig,Varma, Rajender S.
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p. 398 - 417
(2013/03/14)
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- A new facile approach to N-alkylpyrroles from direct redox reaction of 4-hydroxy-l-proline with aldehydes
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An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-l-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.
- Zou, Zhiqin,Deng, Zejun,Yu, Xinhong,Zhang, Manman,Zhao, Sihan,Luo, Ting,Yin, Xin,Xu, Hui,Wang, Wei
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experimental part
p. 43 - 49
(2012/03/13)
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- O-Iodoxybenzoic acid (IBX): A versatile reagent for the synthesis of N-substituted pyrroles mediated by β-cyclodextrin in water
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O-Iodoxybenzoic acid (IBX), a very mild and efficient hypervalent iodine(V) reagent, aromatizes diversely substituted 1-benzylpyrrolidines and N-substituted l-proline analogues to the corresponding substituted pyrroles in good to excellent yields under mild conditions mediated by β-cyclodextrin in water at room temperature. To the best of our knowledge, this is the first report on IBX, promoting complete aromatization leading to N-benzylpyrroles from the corresponding saturated five membered heterocyclic derivatives in water medium.
- Narayana Murthy,Nageswar
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supporting information; experimental part
p. 4481 - 4484
(2011/09/19)
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- Magnetic Nanoparticle-Supported Glutathione as a Sustainable Organocatalyst
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This invention relates to the use of nano-organocatalysts, and, more specifically, to the use of magnetic nanomaterial-supported organocatalysts. It is an object of the present invention to provide “green” catalysts and protocols. According to one embodiment of the invention, a nano-organocatalyst in the form of a magnetic nanomaterial-supported organocatalyst is provided. According to other embodiments of the invention, glutathione and cysteine are provided as organocatalysts and magnetic nanomaterial-supported glutathione and magnetic nanomaterial-supported cysteine are provided for use as nano-organocatalysts. According to another embodiment of the invention, a method of using a recyclable magnetic nanomaterial-supported organocatalyst using a totally benign aqueous protocol, without using any organic solvent in the reaction or during the workup, is provided. According to a further embodiment of the invention, a recyclable magnetic nanomaterial-supported organocatalyst for various organocatalytic reactions, including but not limited to Paal-Knorr reactions, aza-Michael addition and pyrazole synthesis, is provided.
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Page/Page column 6-8
(2011/04/14)
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- Trans-4-Hydroxy-l-proline: A novel starting material for N-alkylpyrroles synthesis
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The reaction of aldehydes with trans-4-hydroxy-l-proline was studied for the first time, resulting in the formation of N-alkylpyrroles in good to excellent yields, via decarboxylation followed by redox isomerization under neutral conditions. The neutral c
- Vijay Kumar,Rama Rao
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experimental part
p. 3237 - 3239
(2011/06/28)
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- Nano-organocatalyst: magnetically retrievable ferrite-anchored glutathione for microwave-assisted Paal-Knorr reaction, aza-Michael addition, and pyrazole synthesis
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Postsynthetic surface modification of magnetic nanoparticles by glutathione imparts desirable chemical functionality and enables the generation of catalytic sites on the surfaces of ensuing organocatalysts. In this article, we discuss the developments, unique activity, and high selectivity of nano-organocatalysts for microwave-assisted Paal-Knorr reaction, aza-Michael addition, and pyrazole synthesis. Their insoluble character coupled with paramagnetic nature enables easy separation of these nano-catalysts from the reaction mixture using external magnet, which eliminates the requirement of catalyst filtration.
- Polshettiwar, Vivek,Varma, Rajender S.
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experimental part
p. 1091 - 1097
(2010/03/25)
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- Magnetic nanoparticle-supported glutathione: A conceptually sustainable organocatalyst
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A conceptually novel nanoparticle-supported and magnetically recoverable organocatalyst has been developed, which is readily prepared from inexpensive starting materials in a truly sustainable manner; which catalyzes the Paal-Knorr reaction with high yield in pure aqueous medium that avoids the use of toxic organic solvents, even in the workup step.
- Polshettiwar, Vivek,Baruwati, Babita,Varma, Rajender S.
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supporting information; experimental part
p. 1837 - 1839
(2009/10/23)
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