Iodine‐Mediated Synthesis of 2‐Arylbenzoxazoles, 2‐Arylbenzimidazoles, and 1,3,5‐Trisubstituted Pyrazoles

Ponnala, Shashikanth; Sahu, Devi Prasad

doi:10.1080/00397910600638879

Cited by 49 publications

(14 citation statements)

References 26 publications

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“…The most important approaches are: (i) condensation of 2-aminopyridine with α-halocarbonyl compounds In recent years, Iodine has proved to be a very useful catalyst in carrying out synthesis of variety of heterocycles such as coumarins 22 , quinolines 23 , benzoxazoles 24 , benzimidazoles 25 and lactones 26 . Iodine has received increasing attention as an inexpensive, non-toxic and readily available catalyst for organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

Iodine-catalyzed three component reaction: a novel synthesis of 2-aryl-imidazo[1,2-a]pyridine scaffolds

Puttaraju

Shivashankar

2013

RSC Adv.

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A facile and efficient protocol for the synthesis of novel imidazo[1,2-a]pyridines has been developed by one-pot reaction of aromatic aldehydes with 2-amino-5-chloropyridine and tertbutylisocyanide in the presence of I 2 in toluene at 70 °C . The present approach offers the advantages of simple methodology, clean, high atom-economy, mild condition, short reaction time, wide substrate scope, low environmental impact and high yield. Key WordsIodine, Imidazopyridines, Imidazo[1,2-a]pyridine, 2-aminopyridine, tert-butylisocyanide. IntroductionMulti-component synthesis have received considerable attention of organic chemists and emerged as a powerful tool for the construction of novel and complex molecular structures due to their advantages over conventional multistep synthesis. The major advantages of MCR's include low cost, shorter reaction times, high atom economy, energy saving and avoidance of time consuming and expensive protection, deprotection, isolation and purification process Result and discussionFirst the optimization of the reaction was studied for which the reaction of 2-chloropyridine-3-carbaldehyde, 5-chloro-pyridin-2-ylamine and tert-butylisocyanide was selected as a The role of solvents on the synthesis of imidazo[1,2-a]pyridine was then studied and the results are depicted (Table 2). Replacing the ethanol by chloroform produced the model in an A probable mechanistic pathway for the formation of imidazo[1,2-a]pyridine is outlined, ConclusionIn conclusion, a straightforward and efficient protocol for the one pot synthesis of Exprimental General informationThe melting points were determined by open capillary method using electric melting point apparatus and are uncorrected. The IR spectra (KBr disc) were recorded on a Shimadzu-8400SFT-IR Spectrophotometer.1 H NMR spectra were recorded on Bruker 300 MHz spectrometer and solution. The organic layer was separated and aqueous layer was extracted with ethyl acetate (15 ml X 3). The combined organic phase were washed with water, dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford a crude product which was purified on silica gel using hexane and ethyl acetate (7:3). 56.9, 104.5, 110.8, 117.3, 120.7, 121.3, 121.8, 123.2, 124.5, 126.0, 127.0, 128.6, 154.5 55.9, 117.8, 120.5, 121.7, 122.7, 125.7, 126.4, 131.1, 136.6, 140.7, 148.8, 149 3, 30.5, 56.8, 117.3, 119.9, 121.4, 122.8, 125.3, 125.6, 126.5, 132.3, 140.0, 140 C, 60.08: H, 5.67: N, 13.14: S, 10.02. Found: C, 59.91: H, 5.54: N, 13.01: S, 9.97. 0, 56.7, 109.8, 113.3, 117.5, 120.0, 120.7, 121.6, 124.7, 126.0, 130.8, 140.6, 151.8 56.7, 109.8, 113.3, 117.5, 120.0, 120.7, 121.6, 124.7, 126.0, 130.8, 140.6, 151.8 55, 57.31, 105.08, 114.07, 114.11, 117.26, 117.92, 121.14, 131.17, 140.89, 140.93, 145.86, 149.71, 150.56, 152.50 N-tert-butyl-6-chloro-2-(1H-imidazol-4-yl)H-imidazo[1,2-a]pyridin-3-amine (2g)

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Section: Introductionmentioning

confidence: 99%

Iodine-catalyzed three component reaction: a novel synthesis of 2-aryl-imidazo[1,2-a]pyridine scaffolds

Puttaraju

Shivashankar

2013

RSC Adv.

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“…Molecular iodine has several advantages as it is inexpensive, readily available, less toxic than alternatives, and a moisture-stable catalyst for organic transformations. Many organic reactions using molecular iodine as catalyst are often associated with mild conditions, short reaction times and simple work-up procedures [47][48][49][50][51][52][53].…”

Section: Introductionmentioning

confidence: 99%

An efficient one-pot synthesis of 2-oxazolines with molecular iodine under ultrasound irradiation

et al. 2015

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“…However, this strategy results in the formation of 4,5-dihydro-1 H -pyrazoles (pyrazolines) that need to be further oxidized to corresponding pyrazoles. For this oxidative aromatization of pyrazolines to pyrazoles, various reagents have been employed such as I 2 , 17 Bi(NO 3 ) 3 .5H 2 O, 18 MnO 2 , 19 DDQ, 20 Pd/C, 21 NaOEt, 22 PhI(OAc) 2 , 23 TBBDA, 24 and ionic liquid. 25, 26 However, many of these oxidative methods suffer from relatively high oxidant loading, use of strong oxidants and chlorinated organic solvents, harsh conditions, poor yields, and longer reaction time.…”

Section: Introductionmentioning

confidence: 99%

Copper triflate-mediated synthesis of 1,3,5-triarylpyrazoles in [bmim][PF6] ionic liquid and evaluation of their anticancer activities

et al. 2013

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A simple, efficient, and environment friendly protocol for the synthesis of 1,3,5-triarylpyrazole and 1,3,5-triarylpyrazolines in [bimm][PF6] ionic liquid mediated by Cu(OTf)2 is described. The reaction protocol gave 1,3,5-triarylpyrazoles in good to high yields (71-84%) via a one-pot addition–cyclocondensation between chalcones and arylhydrazines, and oxidative aromatization without requirement for an additional oxidizing reagent. The catalyst can be reused up to four cycles without much loss in the catalytic activity. The pyrazoles (4a-o) and pyrazolines (3a-n) were evaluated for antiproliferative activity in SK-OV-3, HT-29, and HeLa human cancer cells lines. Among all compounds, 3b inhibited cell proliferation of HeLa cells by 80% at a concentration of 50 μM.

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Iodine‐Mediated Synthesis of 2‐Arylbenzoxazoles, 2‐Arylbenzimidazoles, and 1,3,5‐Trisubstituted Pyrazoles

Cited by 49 publications

References 26 publications

Iodine-catalyzed three component reaction: a novel synthesis of 2-aryl-imidazo[1,2-a]pyridine scaffolds

Iodine-catalyzed three component reaction: a novel synthesis of 2-aryl-imidazo[1,2-a]pyridine scaffolds

An efficient one-pot synthesis of 2-oxazolines with molecular iodine under ultrasound irradiation

Copper triflate-mediated synthesis of 1,3,5-triarylpyrazoles in [bmim][PF6] ionic liquid and evaluation of their anticancer activities

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