One pot synthesis of substituted imidazopyridines and thiazoles from styrenes in water assisted by NBS

Shinde, Mahesh H.; Kshirsagar, Umesh A.

doi:10.1039/c5gc02771c

Cited by 69 publications

(23 citation statements)

References 56 publications

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“…The present reaction provides a simple and straightforward access from readily available materials (nitriles, and Na 2 S$9H 2 O) to thioamides, which permits rapid access to various important compounds. For instance, the 1,2,4-thiadiazole 3a was isolated in 95% yield (Scheme 3a), 33 Moreover, styrene with NBS and subsequent addition of thiobenzamide 2a in water provided 2,4-diarylsubstituted thiazole 4a in 72% yield (Scheme 3b). 34 Furthermore, thiobenzamide 2a with iodobenzene to provide 5a in 57% yield, (Scheme 3c).…”

Section: Resultsmentioning

confidence: 99%

A efficient protocol for the synthesis of thioamides in [DBUH][OAc] at room temperature

Cao

Zheng

et al. 2018

RSC Adv.

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A novel, simple and eco-friendly method to synthesize thioamides from aryl nitriles and sodium sulfide (Na 2 S$9H 2 O) catalyzed by 1,8-diazabicyclo[5,4,0]at room temperature was developed in this paper. In this reaction, readily available inorganic salt (Na 2 S$9H 2 O) serves as the sulfur source, and various functional groups of aryl nitriles were well tolerated at room temperature. In addition, the products were easily separated from the IL which could be reused at least five times without considerable loss of its activity and applied in the green, concise synthesis of ethionamide.

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Section: Resultsmentioning

confidence: 99%

A efficient protocol for the synthesis of thioamides in [DBUH][OAc] at room temperature

Cao

Zheng

et al. 2018

RSC Adv.

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“…Shinde et al . reported the preparation of thiazoles ( 95 ) employing styrenes ( 93 ), thioamides ( 94 ) with NBS ( N ‐Bromo succinimide).…”

Section: Synthesis Of Thiazolesmentioning

confidence: 99%

An Overview of Recent Developments in the Synthesis of Substituted Thiazoles

et al. 2020

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Thiazole frame work represents a vital pharmacophore in several areas of chemistry. Consequently, several synthetic protocols to construct and functionalize this core, in an attempt to generate diverse thiazole containing architectures have been developed by various researchers across the globe. These wide range of methodologies developed will allow the access to fully decorated thiazole containing new chemical entities that can find various application in the field of medicinal chemistry, agrochemicals and material science. This review will provide an insight in to the various synthons used in construction and diversification of this core. Diversely functionalized thiazole analogs are considered as a vital azole framework present in many natural products. This prominent heterocycle also constitutes an important pharmacophore in medicinal chemistry, in agrochemicals and in molecules for material science applications. All these above‐mentioned features of thiazole necessitates the continuous development of efficient methods to access this heterocycle. Accordingly, various researchers across the globe have come up with efficient synthetic protocols in an attempt functionalize different positions of this important scaffold. This review aims at highlighting some of the latest synthetic approaches to di/tri‐substituted thiazole analogs which are known to possess a wide spectrum of biological activities.

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“…N‐Bromosuccinimide (NBS) is a versatile reagent for synthetic organic chemistry, and has numerous applications as the source of cationic bromine, bromine radical, oxidant, and nucleophilic nitrogen . Recently, Kshirsagar reported a one pot synthesis of substituted imidazopyridines and thiazoles from styrene in water assisted by NBS, which achieves NBS promoted, simple, easy handling, and economical method for the construction of diverse heterocyclic building blocks (Scheme ). In addition, they proposed a possible mechanism for the title reaction (Scheme ): the mixture of NBS and styrene to form bromonium ion ( 1 → 1A ), H 2 O promoted the formation of bromohydrin ( 1A → 2A ), NBS mediated oxidation of a secondary benzylic alcohol via hypobromite to form phenacyl bromide ( 2A → 3A → 4A ), condensation of phenacyl bromide and 2‐aminopyridine furnished the product imidazo[1,2‐ a ]pyridine ( 4A → Pr ).…”

Section: Introductionmentioning

confidence: 99%

Mechanistic insights into N‐Bromosuccinimide‐promoted synthesis of imidazo[1,2‐a]pyridine in water: Reactivity mediated by substrates and solvent

et al. 2018

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The mechanism of N-Bromosuccinimide (NBS) promoted synthesis of imidazo [1,2-a]pyridine in water as well as the effective activation modes of NBS was investigated by Density Functional Theory (DFT) calculations. Two main mechanisms that differ in the reaction sequence of substrate were explored: styrene with NBS then followed by 2-aminopyridine (M1) or simultaneously with NBS and 2-aminopyridine (M2), and water-assisted M2 is the more favored one. We found that the adding sequence of 2-aminopyridine affects profoundly on the title reaction. Moreover, upon the assistance of water and NBS, the preferential mechanistic scenario involves three major processes: nucleophilic addition, stepwise H-shift and intramolecular cyclization, three-step deprotonation, rather than a classical bromonium ion species. Specifically, the cooperative interaction of NBS and water plays a critical role in the title reaction. Water acts as solvent, reactant, anchoring, stabilizer, and catalyst. NBS promotes the above three processes by the effective forms of Br + /Br − , succinimide, and its ethanol isomer. Furthermore, noncovalent interactions between catalysts and substrates are responsible for the different reactive activities of M1 and M2. Our results indicate that simultaneous adding of all reactants is recommended toward economical synthesis.

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One pot synthesis of substituted imidazopyridines and thiazoles from styrenes in water assisted by NBS

Abstract: Heating of commercially available styrenes with NBS in water followed by reaction with 2-aminopyridines and thioamides afforded important heterocyclic scaffolds in a one pot procedure.

Cited by 69 publications

References 56 publications

A efficient protocol for the synthesis of thioamides in [DBUH][OAc] at room temperature

A efficient protocol for the synthesis of thioamides in [DBUH][OAc] at room temperature

An Overview of Recent Developments in the Synthesis of Substituted Thiazoles

Mechanistic insights into N‐Bromosuccinimide‐promoted synthesis of imidazo[1,2‐a]pyridine in water: Reactivity mediated by substrates and solvent

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