Nanosized magnesium oxide as catalyst for the rapid and green synthesis of substituted 2-amino-2-chromenes

Kumar, Dalip; Reddy, V. Buchi; Mishra, Braj Gopal; Rana, Rohit; Nadagouda, Mallikarjuna N.; Varma, Rajender S.

doi:10.1016/j.tet.2007.02.019

Cited by 218 publications

(74 citation statements)

References 19 publications

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“…Furthermore, some of these catalysts such as MgO can only catalyze the condensation reaction of aromatic aldehydes, malononitrile and Į-naphtol not E-naphtol. The development of an environmentally benign and simple procedure for synthesis of 2-amino-2-chromenes has thus become particularly fascinating and remains a great challenge [96][97][98].…”

Section: Scheme 26mentioning

confidence: 99%

Basic ionic liquids. A short review

Hajipour

Rafiee

2009

JICS

173

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Basic ionic liquids as environmental-friendly solvents and catalysts with high activity and selectivity and easily recovered materials were used to replace traditional bases such as KOH, NaOH, K 2 CO 3 , NaHCO 3 , NaOAc, triethylamine, or tetrabutylammonium acetate. Using the traditional bases generally suffered from disadvantages such as waste production, corrosion and environmental problems. Basic ionic liquids offering a new possibility for developing environmentally friendly basic catalysts due to the combination of the advantages of inorganic bases and ionic liquids. They are flexible, nonvolatile, noncorrosive, and immiscible with many organic solvents. Basic ionic liquids (BILs) have been used in base-catalyzed processes such as Michael addition, Markovnikov addition, Knoevenagel condensation, Henry reaction, Mannich reaction, oximation, FeistBenary reaction and etc. In this short review, we wish to present an overview of the types, properties, synthesis and applications of basic ionic liquids.

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Section: Scheme 26mentioning

confidence: 99%

Basic ionic liquids. A short review

Hajipour

Rafiee

2009

JICS

173

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“…The recyclability of the catalyst makes the reaction economically and potentially viable for commercial applications. Multi-component one-pot condensation reaction A nanosized magnesium oxide catalyzed threecomponent condensation reaction of aldehyde, malononitrile, and a-naphthol proceeds rapidly in water/PEG to afford corresponding 2-amino-2-chromenes in high yields at room temperature (Scheme 19) (56). The greener protocol is found to be fairly general and the catalyst is reused in subsequent reactions with consistent activity.…”

Section: Metal-catalyzed Reactionsmentioning

confidence: 99%

“Greener” chemical syntheses using mechanochemical mixing or microwave and ultrasound irradiation

Varma

2007

Green Chemistry Letters and Reviews

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Various emerging ''greener'' strategic pathways, researched primarily in the author's own laboratory, are summarized. They include solvent-free mechanochemical methods that involve the use of hypervalent iodine reagents at room temperature for the synthesis of heterocyclic entities, and useful conversion of ketones into b-keto sulfones and their a-tosyloxy derivatives in high yields. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of less-expensive and recyclable mineral supports, such as alumina, silica, clay, or ''doped'' surfaces, is described; it is applicable to a wide range of cleavage, condensation, cyclization, rearrangement, oxidation, and reduction reactions, including rapid one-pot assembly of heterocyclic compounds from in situ generated reactive intermediates. The strategy is adaptable to multi-component reactions, e.g. Ugi and Biginelli reactions, for rapid assembly of a library of compounds. Synthesis of a wide variety of significant precursors and intermediates, namely enones, imines, enamines, nitroalkenes, and oxidized sulfur species, is possible and their value in concise MW synthesis of 2-aroylbenzofurans and thiazole derivatives is illustrated. Ultrasound-and MW-assisted solventless preparation of ionic liquids and their application in alkylation and metal-catalyzed multi-component reactions are described. With a view to consume greenhouse gas, carbon dioxide (CO 2 ), efficient reaction of epoxides with CO 2 provides ready access to cyclic carbonates using only a catalytic amount of recyclable indium-based ionic liquid. MW heating in aqueous reaction media enables expeditious N-alkylation reactions of amines and hydrazines to afford a series of heterocyclic ring systems, such as N-azacycloalkanes, 4,5-dihydropyrazoles, and pyrazolidines. A general and expeditious MW-enhanced nucleophilic substitution approach uses easily accessible starting materials such as halides or tosylates in reaction with alkali azides, thiocyanates, or sulfinates in the absence of any phase transfer catalyst to produce azides, thiocyanates, and sulfones, respectively, wherein a variety of reactive functional groups are tolerated. A three-component condensation (MCC) approach for the synthesis of useful 2-amino-2-chromenes is described using a recyclable nanosized magnesium oxide catalyst in aqueous poly (ethylene glycol) (PEG) medium at room temperature. A general greener approach to shape-selective generation of nanomaterials is summarized including their potential application as nanocomposites.

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“…18 Very recently, nano-metal oxides have been used in organic synthesis and these include copper(II) oxide in the synthesis of 1,4-dihydropyridines, 19 and as an effective catalyst for the CO and NO oxidation, as well as in the oxidation of volatile organic pollutants. 20 Similarly, nano ZnO in Knoevenagel condensation, 21 and nano MgO in the synthesis of 2-amino-2-chromenes 22 have been reported. Over the past two decades, several methods have been developed for the preparation of nc-ZrO 2 , including sol-gel, 23 hydrothermal/solvothermal, 24 emulsion precipitation, 25 and microwave/sonication-assisted co-precipitation 26 methods.…”

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confidence: 90%

Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

et al. 2011

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Nanocrystalline zirconium(IV) oxide (nc-ZrO 2 ) possessing high surface area was synthesized by a low temperature eco-friendly solution combustion method using a new organic fuel alanine. The powder XRD, SEM and surface area measurements were carried out for characterization of nc-ZrO 2 . The powder XRD results revealed that, the nc-ZrO 2 has the pure tetragonal phase. The crystallite size calculated by Scherrer's formula and BET surface area were found to be ca. 53-57 nm and ca. 275 m 2 /g, respectively. SEM micrograph exhibited the macroporous nature of the powder. nc-ZrO 2 has been employed as a catalyst for the solvent-free synthesis of 3,4-dihydropyrimidin-2-ones (DHPMs) by a microwave (MW) assisted one-pot, multicomponent Biginelli condensation reaction of araldehydes, ethylacetoacetate and urea or thiourea. DHPMs are obtained in good to excellent yields (85%-96%) under this reaction condition within short interval of time (10-20 min).

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Nanosized magnesium oxide as catalyst for the rapid and green synthesis of substituted 2-amino-2-chromenes

Cited by 218 publications

References 19 publications

Basic ionic liquids. A short review

Basic ionic liquids. A short review

“Greener” chemical syntheses using mechanochemical mixing or microwave and ultrasound irradiation

Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

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Nanosized magnesium oxide as catalyst for the rapid and green synthesis of substituted 2-amino-2-chromenes

Cited by 218 publications

References 19 publications

Basic ionic liquids. A short review

Basic ionic liquids. A short review

“Greener” chemical syntheses using mechanochemical mixing or microwave and ultrasound irradiation

Combustion Derived Nanocrystalline‐ZrO2 and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation

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Combustion Derived Nanocrystalline‐ZrO₂ and Its Catalytic Activity for Biginelli Condensation under Microwave Irradiation