نتایج جستجو برای: base catalyst

تعداد نتایج: 299630  

Journal: :Organic & biomolecular chemistry 2010
Pattama Saisaha Dirk Pijper Ruben P van Summeren Rob Hoen Christian Smit Johannes W de Boer Ronald Hage Paul L Alsters Ben L Feringa Wesley R Browne

A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H(2)O(2) is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions....

Journal: :Organic & biomolecular chemistry 2012
Wenyi Li Xiaodong Liu Zhifeng Mao Qiao Chen Rui Wang

A highly efficient catalyst system assembled from enantiomerically pure diaminocyclohexane and Ni(OAc)(2) is, for the first time, used to catalyze the cascade Michael-Henry reaction of various diones and substituted nitroalkenes. A series of polyfunctionalized bicyclo[3.2.1]octane derivatives containing four stereogenic centers are prepared with excellent enantioselectivities (up to >99% ee) an...

2018
Romain Sallio Stéphane Lebrun Frédéric Capet Francine Agbossou-Niedercorn Christophe Michon Eric Deniau

A new asymmetric organocatalyzed intramolecular aza-Michael reaction by means of both a chiral auxiliary and a catalyst for stereocontrol is reported for the synthesis of optically active isoindolinones. A selected cinchoninium salt was used as phase-transfer catalyst in combination with a chiral nucleophile, a Michael acceptor and a base to provide 3-substituted isoindolinones in good yields a...

2017
Pedro Leo Gisela Orcajo David Briones Guillermo Calleja Manuel Sánchez-Sánchez Fernando Martínez

The activity and recyclability of Cu-MOF-74 as a catalyst was studied for the ligand-free C-O cross-coupling reaction of 4-nitrobenzaldehyde (NB) with phenol (Ph) to form 4-formyldiphenyl ether (FDE). Cu-MOF-74 is characterized by having unsaturated copper sites in a highly porous metal-organic framework. The influence of solvent, reaction temperature, NB/Ph ratio, catalyst concentration, and b...

The cross-coupling reaction between phenylboronic acid and various types of aryl halides (Suzuki reaction) was carried out using a catalytic amount of a new palladium catalyst (1-benzyl-3-(1-benzyl-1-methylpyrrolidin-1-ium-2-yl) pyridin-1-ium palladium chloride [DBNT][PdCl4]) in poly (ethylene glycol) (PEG-200) in the presence of KOH as the base. This new catalyst was synthesized and...

An organosuperbase (N,N-dimethylbiguanide) immobilized on mesoporous and magnetically separable silica supports, was found for the first time, to act as a highly-stable, scalable and efficient heterogeneous catalyst for the Henry reaction under mild and neutral condition. Several factors such as catalyst amount, solvent and reaction time concerning the reactivity were also discussed. The proced...

2014
Ken Motokura Toshihide Baba Yasuhiro Iwasawa

This chapter deals with acid–base bifunctional heterogeneous catalyst surfaces with organofunctional groups. One of the most important issues for bifunctional heterogeneous catalysis is the coexistence of incompatible catalytic species, such as acid and base, nearby on a same solid particle surface. In nucleophilic reactions, acid–base bifunctional catalysts enable the activation of both nucleo...

Silica-bonded N-propyldiethylenetriamine (7) is employed as a recyclable heterogeneous solid base catalyst for the synthesis of 2-amino-3,5-dicarbonitrile-6-thiopyridines through pseudo four-component condensation reaction between aromatic aldehydes, malononitrile, and 2-amino-thiophenol in refluxing ethanol. Silica-bonded N-propyldiethylenetriamine showed much the same efficiency when used in ...

Several new 2-pyridyl-4-thiazolidinones are synthesized in an efficient manner evading using any catalyst or base. Simple workup procedure, good yields, and mild reaction conditions are the salient features of this method. All the synthesized compounds are screened for antimicrobial activity against several organisms.

2015
Priyanka Srivastava Pratima Jain

An efficient and facile synthesis of fatty acid methyl esters (FAMEs) using sunflower oil and methanol has been carried out in the presence of a solid base Mg-Al-CO3 hydrotalcite heterogeneous catalyst. This protocol promotes the environment friendly conditions as the hydrotalcites are non toxic, recyclable, takes less reaction time and is easy to work up. The hydrotalcite showed high activity ...

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