InBr3-catalyzed three-component, one-pot synthesis of imidazo[1,2-a]pyridines

Reddy, B. V. Subba; Reddy, P. Sivaramakrishna; Reddy, Y. Jayasudhan; Yadav, J. S.

doi:10.1016/j.tetlet.2011.08.110

Cited by 67 publications

(25 citation statements)

References 36 publications

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“…Intermediate I was readily detected by gas chromatography coupled to mass spectrometry when analyzing crude reaction mixtures, while intermediate III was not detected. This result agrees with the mechanistic proposal made by other authors, 35,38,43 with imine formation from aldehyde and amine as a faster step than the propargyl alcohol formed between aldehyde and alkyne which was not observed.…”

Section: Resultssupporting

confidence: 93%

“…In this context, a very mild methodology using a single catalyst as the active specie was published using iodine in water while the use of indium bromide as Lewis acid catalyst requires the presence of triethylamine as additive and molecular sieves yielding a series of substituted imidazo[1,2-a]pyridines. 34,35 One report shows a very clean solvent and catalyst-free synthesis of imidazo [1,2-a]pyridines from 2-aminopyridine and α-bromoacetophenone. 36 Copper(II) salts were also proven useful on intramolecular oxidative cyclization from haloalkynes and 2-aminopyridines.…”

Section: Introductionmentioning

confidence: 99%

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Imidazo[1,2-a]pyridine A3-Coupling Catalyzed by a Cu/SiO2 Material

Salles¹,

Silva²,

Radatz³

et al. 2019

J. Braz. Chem. Soc.

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In this work, we report the preparation of a copper-silica material (Cu/SiO 2) by a sol-gel methodology and its characterization concerning composition and textural properties. The Cu/SiO 2 material was successfully applied as a Lewis acid heterogeneous catalyst for the A 3-coupling from 2-aminopyridine, aldehydes and alkynes to imidazo[1,2-a]pyridines (45-82%), which are relevant pharmacological scaffolds. The synthesis shows a number of advantages, such as easy separation from the reaction media and the minimal formation of metal aqueous wastes. Investigation of the mechanism supports the involvement of the formation of reaction intermediates inside the pores of the mesoporous material prior to 5-exo-dig cyclization.

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Section: Resultssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Imidazo[1,2-a]pyridine A3-Coupling Catalyzed by a Cu/SiO2 Material

Salles¹,

Silva²,

Radatz³

et al. 2019

J. Braz. Chem. Soc.

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“…Various methods have been reported for the synthesis of substituted imidazo[1,2-a]pyridines. The most important approaches embrace [ 20 ]: (1) condensation of 2-aminopyridine with α-halocarbonyl compounds [ 21 , 22 , 23 , 24 ], (2) one-pot condensations of isocyanide, aldehydes, and 2-aminopyridines [ 25 , 26 , 27 ], and (3) three-component reactions of 2-aminopyridines, aldehydes, and alkynes [ 28 , 29 , 30 ]. Although new methods are being published continuously, the synthesis of imidazo[1,2-α]pyridines using 2-aminopyridines with α-haloketones and α-haloaldehydes is still the most popular [ 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of 2-Phenylimidazo[1,2-α]pyridines from Acetophenone, [Bmim]Br3 and 2-Aminopyridine under Solvent-Free Conditions

Zhang

Xie

2012

Molecules

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“…Mechanistically, the synthetic process undergoes a consecutive A 3 -coupling and cycloisomerization, with the nitrogen atom of the 2-aminopyridine working as an extra nucleophile and allowing the preparation of the bicyclic structure. [29] Sarmah et al reported the synthesis of a library of benzo[h]quinolines (16 examples) under MAOS and solvent-free conditions. The catalyst used was indium triflate and the desired tricyclic structures were obtained in very good to excellent yields with short reaction times (Scheme 8C).…”

Section: A 3 -Coupling Reactionsmentioning

confidence: 99%

A Decade of Indium‐Catalyzed Multicomponent Reactions (MCRs)

2020

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In the context of synthetic chemistry, Indium is one of the least explored elements of the notorious group 13 of the periodic table and has not attracted quite the same amount of attention as its fellow members, Aluminium and Boron, which have shown unprecedented synthetic applications for more than half a century. Nonetheless, Indium has emerged in recent years as a very valuable catalyst for multicomponent reactions. From the use of indium powder or easily accessible and cheap indium salts to more complex indium‐based metal‐organic frameworks or nanoparticles, a plethora of applications has been described throughout this last decade, showcasing not only the versatility of indium catalysis but also how much there is still to be explored. In the aftermath of the international year of the periodic table of the chemical elements in 2019, we navigated through the large inventory of multicomponent reactions (MCRs) to encounter the types of useful reactions leading to important target compounds (many of which are biologically active) catalyzed by this d‐block post‐transition metal.

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InBr3-catalyzed three-component, one-pot synthesis of imidazo[1,2-a]pyridines

Cited by 67 publications

References 36 publications

Imidazo[1,2-a]pyridine A3-Coupling Catalyzed by a Cu/SiO2 Material

Imidazo[1,2-a]pyridine A3-Coupling Catalyzed by a Cu/SiO2 Material

One-Pot Synthesis of 2-Phenylimidazo[1,2-α]pyridines from Acetophenone, [Bmim]Br3 and 2-Aminopyridine under Solvent-Free Conditions

A Decade of Indium‐Catalyzed Multicomponent Reactions (MCRs)

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