Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction

Neuhaus, William C.; Bakanas, Ian; Lizza, Joseph R.; Boon, C.; Moura‐Letts, Gustavo

doi:10.1080/17518253.2016.1149231

Cited by 22 publications

(4 citation statements)

References 27 publications

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“…On the basis of the already established reactivity pattern among hydrazines, it was expected that the electronic and steric properties of substituted hydrazines would drastically affect the outcome of this reaction . Thus, it was observed that p ‐chlorophenyl‐, phenyl‐, and p ‐fluorophenylhydrazine provided the tetrasubstituted pyrazole in great yields as the only isomer (Entries 1–3).…”

Section: Resultsmentioning

confidence: 98%

Synthesis of Tetrasubstituted Pyrazoles from Substituted Hydrazines and β‐Keto Esters

Bakanas

Moura‐Letts

2016

Eur J Org Chem

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Herein we report the synthesis of tetrasubstituted pyrazoles from simple hydrazines and β‐keto esters under mild, basic conditions. This reaction enables the selective synthesis of pyrazolones, alkoxypyrazoles, and tetrasubstituted pyrazoles for a large variety of aromatic hydrazines and substituted β‐keto esters with high yields and selectivities. This method permits access to highly complex pyrazole scaffolds with four orthogonal diversification groups.

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Section: Resultsmentioning

confidence: 98%

Synthesis of Tetrasubstituted Pyrazoles from Substituted Hydrazines and β‐Keto Esters

Bakanas

Moura‐Letts

2016

Eur J Org Chem

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“…These catalytic systems suffer from considerable drawbacks such as low yield, harsh or delicate reaction condition, by‐products, high temperatures, prolonged reaction times and tedious work‐up procedures. Few catalytic systems have been introduced for the Fischer indole reaction involving ionic liquid as reaction medium with added Lewis acid catalyst or use of task‐specific acidic ionic liquids to work as dual solvent–catalysts in solution or solvent‐free medium at various temperatures . Indole and its derivatives constitute a major class of N‐heterocycles in various biochemical processes as they are a part of some essential amino acids and most proteins.…”

Section: Introductionmentioning

confidence: 99%

“…for the Fischer indole reaction in water at 80–100°C for 0.5–6 h reaction time . Neuhaus and co‐workers also conducted the Fischer indole synthesis of wide variety of hydrazine and ketones in the presence of the acidic ionic liquid tetramethylguanidinium propanesulfonic acid trifluoromethyl acetate in water at 90°C . In 2012, Li et al .…”

Section: Introductionmentioning

confidence: 99%

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

Saikia

Puri

Borah

2019

Applied Organom Chemis

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HZSM‐5‐supported Brönsted and Lewis acidic ionic solid 1,3‐disulfoimidazolium chlorozincate materials ([dsim]2[ZnCl4]@HZSM‐5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt‐loaded HZSM‐5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X‐ray diffraction and inductively coupled plasma optical emission spectrometric techniques.

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“…The unique physicochemical properties of these materials place them in the first row of choice as solvent for numerous applications like organic reactions, photochemical reactions, energy devices etc. Trifluoro acetate and trifluoromethane sulphonate anion based protic and aprotic ILs have been used for various applications by different research group such as catalyst and reaction medium for the Fischer indole synthesis; as chiral catalysts for the enantioselective Michael addition reaction; alternative electrolytes for rechargeable aluminium batteries; carbon dioxide, sulphur oxide and carbon capturing . The intermolecular interactions (like; hydrogen bonding, Coulomb charge and dispersion forces) and fundamental properties of ILs are key features to understand the mechanism behind the usability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fluorinated Anion on the Physicochemical, Rheological and Solvatochromic Properties of Protic and Aprotic Ionic Liquids: Experimental and Computational Study

2017

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The essential properties of ionic liquids (ILs) for various applications can be tuned by changing the combination of cations or anions in ILs. This work demonstrates how the structure variations effect the physicochemical, rheological and solvatochromic properties of protic and aprotic ionic liquids. For this, a set of four ionic liquids have been synthesized and characterized through spectral techniques. Thermal stability and phase behaviour of ILs have been analyzed by TGA and DSC. The experimental density, speed of sound and viscosity have been measured as a function of temperature from 293.15 to 343.15 K and an attempt has been made to distinguish the crucial role of counter ions on measured properties. Further, the fluidity and polarity behaviour of hydroxyl ammonium based protic or 1‐alkyl‐1,2,4‐triazolium based aprotic cation and fluorinated anions were investigated through their rheological and polarity parameters at 298.15 K and discussion have been made on the basis of columbic and hydrogen bonding interactions. Interestingly, we found that anions have dominant effect on studied physicochemical properties irrespective of protic/aprotic nature of ionic liquid while the contribution of cations were vital for solvatochromic and rheological properties. Additionally, the ion‐pair interaction energy, dipole moment and hydrogen bonding interactions of studied ILs have been analysed using density functional theory (DFT) calculations to support the experimental findings.

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Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction

Cited by 22 publications

References 27 publications

Synthesis of Tetrasubstituted Pyrazoles from Substituted Hydrazines and β‐Keto Esters

Synthesis of Tetrasubstituted Pyrazoles from Substituted Hydrazines and β‐Keto Esters

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

Effect of Fluorinated Anion on the Physicochemical, Rheological and Solvatochromic Properties of Protic and Aprotic Ionic Liquids: Experimental and Computational Study

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