A Regioselective [4+2] Annulation Approach to 5-Acylindolizine-7-carbonitriles: Generation of Poly-substituted Pyridines

2021 ◽  
Author(s):  
Sunmi Kim ◽  
Jeong Hwa Lee ◽  
Seok Hyun Yoon ◽  
Ikyon Kim
Keyword(s):  
Knoevenagel Condensation ◽  
Wide Range ◽  
Aldol Cyclization ◽  
Substituted Pyridines

Reaction of β-ketonitrile and N-substituted pyrrole-2-carboxaldehyde in the presence of piperidinium acetate in CH3CN permitted regioselective access to 5-acyl-6-arylindolizine-7-carbonitrile through a domino Knoevenagel condensation-intramolecular aldol cyclization sequence. A wide range...

scholarly journals Microwave-assisted urea catalyzed Knoevenagel condensation of aldehydes with active methylene compounds

2020 ◽  
Vol 55 (2) ◽  
pp. 159-164
Author(s):  
WT Purba ◽  
PS Roy ◽  
S Jannat ◽  
SA Begum ◽  
MM Rahman
Keyword(s):  
Microwave Irradiation ◽  
Efficient Method ◽  
Knoevenagel Condensation ◽  
Efficient Catalyst ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Active Methylene Compounds ◽  
Reaction Proceeds ◽  
Active Methylene

Rapid and efficient method for the synthesis of substituted olefins such as 2-(4-chlorophenylmethylene) malononitrile, 2-(4-hydroxyphenylmethylene) malononitrile and 2-cyano-3-(4-hydroxyphenyl) acrylamide etc under the influence of microwave irradiation are described. Urea has been utilized as an efficient catalyst for the Knoevenagel condensation of aldehydes with acidic active methylene compounds such as malononitrile, ethylcyanoacetate and cyanoacetamide to afford substituted olefins under the influence of microwave irradiation. The reaction proceeds smoothly under mild and solvent free conditions and the products are obtained in good yield. The method is applicable for a wide range of aldehydes including aromatic and heterocyclic substrates. Bangladesh J. Sci. Ind. Res.55(2), 159-164, 2020

Base-Promoted Tandem Cyclization for the Synthesis of Polyfunctional 2-Hydroxy-2,3-dihydrofurans from Arylglyoxal Monohydrates and 3-(1H-Indol-3-yl)-3-oxopropanenitrile

Synlett ◽  
2018 ◽  
Vol 29 (14) ◽  
pp. 1926-1932
Author(s):  
Yi Liu ◽  
An-Xin Wu ◽  
Qun Cai ◽  
Hui-Yang Sheng ◽  
Deng-Kui Li
Keyword(s):  
Functional Groups ◽  
Michael Addition ◽  
Knoevenagel Condensation ◽  
One Pot ◽  
Wide Range ◽  
Reaction Proceeds ◽  
Tandem Cyclization ◽  
Arylglyoxal Monohydrates

An efficient base-promoted tandem cyclization for the synthesis of polyfunctional 2-hydroxy-2,3-dihydrofurans from arylglyoxal monohydrates and 3-(1H-indol-3-yl)-3-oxopropanenitrile has been established. The investigation of the mechanism suggested that this reaction proceeds through a Knoevenagel condensation–Michael addition–oxidation–cyclization sequence. This method demonstrates the compatibility with a wide range of functional groups to produce the 2-hydroxy-2,3-dihydrofuran scaffolds in good to excellent yields in one pot.

scholarly journals Unprecedented Coumarin-Pyronin Hybrid Dyes: Synthesis, Fluorescence Properties and Theoretical Calculations

2021 ◽  
Author(s):  
Kevin Renault ◽  
Arnaud Chevalier ◽  
Jérôme Bignon ◽  
Denis Jacquemin ◽  
Jean-Alexandre Richard ◽  
...  
Keyword(s):  
Intramolecular Charge Transfer ◽  
Knoevenagel Condensation ◽  
Theoretical Calculations ◽  
A549 Cells ◽  
Hybrid Structures ◽  
Aryl Ether ◽  
Xanthene Dyes ◽  
Wide Range ◽  
Synthetic Routes ◽  
Nucleophilic Center

A novel class of rosamine dyes bearing a 7-substituted 4-hydroxycoumarin unit as <i>meso</i>-heteroaryl ring is presented. The latent <i>C</i>-nucleophilic character of 4-hydroxycoumarin derivatives (<i>i.e.</i>, their C-3 position as nucleophilic center) has been drawn on in the designing of two unprecedented synthetic routes towards these atypical xanthene dyes. They are based on an effective formal Knoevenagel condensation with either pyronin derivatives or a mixed bis-aryl ether bearing both an aldehyde and a masked phenylogous amine, possibly applicable to a wide range of latent cyclic <i>C</i>-nucleophiles. We also report experimental and theoretical photophysical investigations of these unique coumarin-pyronin hybrid structures and particularly their form low-lying quenching states, some of dark twisted intramolecular charge transfer (TICT) nature, depending on the medium (CHCl<sub>3</sub> and water). Furthermore, two fluorophore compounds <b>9</b> and <b>11</b> have been applied for imaging in paraformaldehyde-fixed A549 cells to gain insights into their permeation and localization.

Knoevenagel Condensation of Phosphinoylacetic Acids with Aldehydes: An Efficient One-Pot Strategy for the Synthesis of P-Functionalized Alkenyl Compounds

Synthesis ◽  
2021 ◽  
Author(s):  
Kamil Dziuba ◽  
Katarzyna Szwaczko ◽  
Sławomir Frynas
Keyword(s):  
Efficient Method ◽  
Knoevenagel Condensation ◽  
Condensation Reaction ◽  
Environmentally Friendly ◽  
Phosphine Oxides ◽  
One Pot ◽  
Practical Procedure ◽  
Synthesis Strategy ◽  
Wide Range ◽  
Knoevenagel Condensation Reaction

AbstractA wide range of commercially available aldehydes have been applied to Knoevenagel condensation reaction to give E-alkenylphosphine oxides and vinylphosphine oxides. The readily available phosphinoylacetic acids derived from P(O)–H compounds were used as the starting materials in the reaction, providing a highly stereoselective and efficient method for constructing α,β-unsaturated phosphine oxides. Moreover, this simple and practical procedure provides an alternative and more environmentally friendly synthesis strategy for this type of P-functionalized alkenyl compounds.

A Facile, Efficient and Solvent-Free Titanium (IV) Ethoxide Catalysed Knoevenagel Condensation of Aldehydes and Active Methylenes

2020 ◽  
Vol 17 (2) ◽  
pp. 107-115
Author(s):  
Manjunatha M. Ramaiah ◽  
Nanjunda Swamy Shivananju ◽  
Priya Babu Shubha
Keyword(s):  
Microwave Irradiation ◽  
Knoevenagel Condensation ◽  
Ethyl Cyanoacetate ◽  
Diethyl Malonate ◽  
Aromatic Aldehydes ◽  
Reaction Rates ◽  
Solvent Free ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Titanium Ethoxide

: Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.

Polyguanidine as a Highly Efficient and Reusable Catalyst for Knoevenagel Condensation Reactions in Water

2013 ◽  
Vol 66 (4) ◽  
pp. 500 ◽  
Author(s):  
Xian-Liang Zhao ◽  
Ke-Fang Yang ◽  
Xuan-Gan Liu ◽  
Chun-Lin Ye ◽  
Li-Wen Xu ◽  
...  
Keyword(s):  
Knoevenagel Condensation ◽  
Knoevenagel Reaction ◽  
Reusable Catalyst ◽  
Efficient Catalyst ◽  
Condensation Reactions ◽  
Highly Efficient ◽  
Wide Range ◽  
Active Methylene Compounds ◽  
Simple Filtration ◽  
Active Methylene

Polyguanidine is used as a novel and highly efficient catalyst in the Knoevenagel reaction of aldehydes with active methylene compounds in water to afford substituted electrophilic alkenes. This method is applicable for a wide range of aldehydes including aromatic and heterocyclic substrates. The polyguanidine catalyst can be recovered by simple filtration and reused many times for the aqueous Knoevenagel reaction without loss of activity.

A Review on Synthesis and Pharmacological Activity of Coumarins and Their Analogs

2020 ◽  
Vol 16 (6) ◽  
pp. 818-836 ◽  
Author(s):  
Moustafa A. Gouda ◽  
Mohammed A. Salem ◽  
Mohamed H. Helal
Keyword(s):  
Knoevenagel Condensation ◽  
Chemical Reactivity ◽  
Biological Activities ◽  
Vitamin K Antagonists ◽  
Biological Properties ◽  
Synthetic Approach ◽  
Wide Range ◽  
Perkin Reaction ◽  
Coumarin Ring ◽  
Substituted Coumarins

Background: Coumarins were reported to possess antimicrobial, antiinflammatory, antiplasmodial, antimalarial, and enzyme inhibitory properties. Furthermore, coumarins are a type of vitamin K antagonists. Coumarins had been first organized through perkin reaction; besides Knoevenagel condensation was mentioned as a critical synthetic approach for the synthesis of 3-substituted coumarins. Moreover, Pechmann, Reformatasky and Witting reactions were stated for the preparation of coumarins. Methods: We undertook a structured search of the method of preparation, the chemical reactivity and biological properties that are associated with coumarins and their analogous. Results: Coumarins display a wide range of Src Kinase and cholinesterase inhibitor activities and application of coumarins as antidiabetic, antipsychotic and antiproliferative agents has been addressed. Other properties of coumarins such as their role in antitumor, anticancer, and as antioxidants have also been reviewed. Conclusion: This review concluded that coumarin ring was mixed with other rings, a synergistic effect for each of the ring in their biological activities was obtained, such compounds were exploited to improve various important molecules which provide scaffolds for drug improvement. These compounds were used to broaden a special molecule that gives scaffolds for drug improvement.

scholarly journals Environmental-friendly one-pot cascade synthesis of 3-cyanopiperidin-2,6-diones

2019 ◽  
Vol 18 (1) ◽  
pp. 165-170 ◽  
Author(s):  
Daniel Paprocki ◽  
Stanisław Berłożecki ◽  
Ryszard Ostaszewski
Keyword(s):  
Natural Products ◽  
Silica Gel ◽  
Knoevenagel Condensation ◽  
Environmentally Friendly ◽  
Aromatic Aldehydes ◽  
Cyanoacetic Acid ◽  
One Pot ◽  
One Pot Synthesis ◽  
Environmental Friendly ◽  
Wide Range

Abstract 3-Cyanopiperidin-2,6-diones are key intermediates in the synthesis of several drugs and natural products. We developed  one-pot synthesis of 3-cyanopiperidin-2,6-diones by Knoevenagel condensation of cyanoacetic acid and aldehydes, followed by addition of cyanoacetic acid, Achmatowicz reaction and decarboxylation. We tested a wide range of aliphatic and aromatic aldehydes. Products were obtained under simple, environmentally friendly conditions and in yields up to 99%. Substrates were stirred in toluene at reflux, and filtered through short pad of silica gel, and the product was purified by recrystallization.

scholarly journals Unprecedented Coumarin-Pyronin Hybrid Dyes: Synthesis, Fluorescence Properties and Theoretical Calculations

2021 ◽  
Author(s):  
Kevin Renault ◽  
Arnaud Chevalier ◽  
Jérôme Bignon ◽  
Denis Jacquemin ◽  
Jean-Alexandre Richard ◽  
...  
Keyword(s):  
Intramolecular Charge Transfer ◽  
Knoevenagel Condensation ◽  
Theoretical Calculations ◽  
A549 Cells ◽  
Hybrid Structures ◽  
Aryl Ether ◽  
Xanthene Dyes ◽  
Wide Range ◽  
Synthetic Routes ◽  
Nucleophilic Center

A novel class of rosamine dyes bearing a 7-substituted 4-hydroxycoumarin unit as <i>meso</i>-heteroaryl ring is presented. The latent <i>C</i>-nucleophilic character of 4-hydroxycoumarin derivatives (<i>i.e.</i>, their C-3 position as nucleophilic center) has been drawn on in the designing of two unprecedented synthetic routes towards these atypical xanthene dyes. They are based on an effective formal Knoevenagel condensation with either pyronin derivatives or a mixed bis-aryl ether bearing both an aldehyde and a masked phenylogous amine, possibly applicable to a wide range of latent cyclic <i>C</i>-nucleophiles. We also report experimental and theoretical photophysical investigations of these unique coumarin-pyronin hybrid structures and particularly their form low-lying quenching states, some of dark twisted intramolecular charge transfer (TICT) nature, depending on the medium (CHCl<sub>3</sub> and water). Furthermore, two fluorophore compounds <b>9</b> and <b>11</b> have been applied for imaging in paraformaldehyde-fixed A549 cells to gain insights into their permeation and localization.

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