The Gewald Synthesis

Sabnis, R. W.

doi:10.1080/01961779408048964

Cited by 59 publications

(25 citation statements)

References 60 publications

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“…A retrosynthetic analysis of these agents suggested that an amino thiophene ester ring would be prepared first using the standard Gewald reaction. [17, 18] Once the thiophene was in hand, the pyrimidine ring could be prepared by converting the amine into a urea followed by cyclizing with the ester under basic conditions.…”

Section: Resultsmentioning

confidence: 99%

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

Dewal

Wani

Vidaillac

et al. 2012

European Journal of Medicinal Chemistry

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Several thieno[2,3-d]pyrimidinediones have been synthesized and examined for antibacterial activity against a range of Gram-positive and Gram-negative pathogens. Two compounds displayed potent activity (2–16 mg/L) against multi-drug resistant Gram-positive organisms, including methicillin, vancomycin-intermediate, and vancomycin-resistant Staphylococcus aureus (MRSA, VISA, VRSA) and vancomycin-resistant enterococci (VRE). Only one of these agents possessed moderate activity (16–32 mg/L) against Gram-negative strains. An examination of the cytotoxicity of these agents revealed that they displayed low toxicity (40–50 mg/L) against mammalian cell and very low hemolytic activity (2–7%). Taken together, these studies suggest that thieno[2,3-d]pyrimidinediones are interesting scaffolds for the development of novel Gram-positive antibacterial agents.

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Section: Resultsmentioning

confidence: 99%

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

Dewal

Wani

Vidaillac

et al. 2012

European Journal of Medicinal Chemistry

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“…From the symmetric ketone 47 the Gewald thiophene synthesis was conducted in a stepwise fashion through Knoevenagel-Cope condensation to give the intermediate 48 followed by base-promoted thiophene cyclization with sulfur. [35][36][37] From the 2-aminothiophene-3-carbonitrile 49a or methyl 2-aminothiophene-3-carboxylate 49b the annulation of pyridine was performed using common pyrimidine annelation with guanidine carbonate 50a or chloroformamidine hydrochloride 50b (Method A, Scheme 19). 129 In a second approach the aldehyde derivative 49c was prepared first in three steps and then annelated under the same conditions as before (Method B, Scheme 19).…”

Section: Synthesis Of Substituted Thieno[23-d]pyrimidinesmentioning

confidence: 99%

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

Puterová¹,

Krutošíková²,

Végh³

2010

Arkivoc

168

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Chemistry of 2-aminothiophenes is arguably one of the most extensive and dynamic field of present-day thiophene research. Since 1961 when first report on the Gewald reaction was reported it became a universal method for synthesis of substituted 2-aminothiophenes and has gained prominence in recent times. The availability of reagents and the mild reaction conditions all contribute to the versatility of this reaction. This review summarizes the synthetic strategies for substituted 2-aminothiophenes. Consequently, details about the proposed mechanism of Gewald-like reactions and the wide scope of substituted 2-aminothiophenes for real life applications.

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“…Although the Gewald reaction has been extensively used in the pharmaceutical industry [12], it is quite surprising that no review emphasising the use of the Gewald reaction in dye chemistry has so far appeared. A few reviews have covered some aspects of the Gewald reaction [6][7][8][9][10][11][12][13][14][15][16][17], but none of the review has focused particularly on dye chemistry. The present review will focus on the use of Gewald chemistry in the synthesis of conventional and functional colourants, specifically azo dyes, fluorescent dyes (coumarin dyes, styryl dyes, thieno [2,3-d]pyrimidine dyes, bithiophene dyes), thiophene analogues of phthalocyanines, and fluorescent whitening agents.…”

Section: Introductionmentioning

confidence: 99%

The Gewald reaction in dye chemistry

Sabnis¹

2016

Coloration Technology

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This review presents the most elegant and promising set of synthetic routes for the synthesis of 2‐aminothiophenes by the Gewald reaction. This reaction has applications in several applied fields, such as pharmaceuticals/biomedicine, agrochemicals, carbohydrate conjugates, sugar cane ripeners, peptide analogues, dyestuffs, and electronic materials; however, the present review will focus on the use of Gewald chemistry in the synthesis of conventional and functional colourants. The Gewald reaction produces 2‐aminothiophene, which is a key intermediate for the diazotisation reaction and for the synthesis of azo dyes, and thus opened the door for new dye chemistry. The reaction produces electron‐withdrawing groups such as CN, COOEt, COOMe, CONH2, and COPh in the 3‐ and/or 5‐position, resulting in bathochromic shifts for the deeper colours of the dyes. The review further reveals the importance of this reaction in the synthesis of azo dyes, fluorescent dyes (coumarin dyes, styryl dyes, thieno[2,3‐d]pyrimidine dyes, bithiophene dyes), thiophene analogues of phthalocyanines, and fluorescent whitening agents.

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The Gewald Synthesis

Cited by 59 publications

References 60 publications

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

The Gewald reaction in dye chemistry

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