Von Pechmann Condensation Research Articles

Chemical and physical analysis of synthesized coumarin compounds: Investigating responses to gamma and neutron radiations

This research investigates the chemical and physical characteristics of three recently synthesized coumarin compounds produced via the von Pechmann condensation mechanism. These compounds were successfully and precisely synthesized, as confirmed by a comprehensive understanding of their chemical composition obtained through combined infrared and NMR analyses. The compounds underwent examination regarding their responses to gamma and neutron radiations, and their mass attenuation coefficients (MAC) were determined using both GATE/Geant4 simulation and NIST-XCOM data. Additionally, the effective removal cross-section values for fast neutrons were calculated employing various methods. All acquired data has been compared with that of water and other materials in the existing literature. Although coumarin compounds might not have intrinsic shielding properties, they have the potential to be part of composite materials designed for specific applications. Comparative analysis with established radiation dosimetry systems showed the coumarin compounds’ attenuation coefficients closely aligning with water, indicating their potential suitability for nuclear applications requiring water-equivalent properties. Further assessment with Geant4 simulation under linac photon beams demonstrated the water-equivalent properties of the coumarin compounds for 6 MV and 18 MV.

Recyclable cellulose nanocrystal supported Palladium nanoparticles as an efficient heterogeneous catalyst for the solvent‐free synthesis of coumarin derivatives via von Pechmann condensation

2‐Amino pyrimidine nanocellulose‐supported Palladium nanoparticles (CNC‐AMPD‐Pd) as a novel bio supported nanocatalyst was prepared and characterized by ICP‐AES, FT‐IR, XRD, SEM, TEM, TGA and EDX techniques. The nanocatalyst demonstrated outstanding performance in Pechmann condensation between different substituted phenols and ethyl acetoacetate to obtain coumarin derivatives in good to excellent yields. The catalyst is easily recycled and reused without loss of the catalytic activity. The combined merits of reusable catalyst and solvent‐free reaction conditions make the condensation with safe operation, no leaching of pd into environment, low pollution, rapid access to products and simple workup.

Synthesis of Novel Anti‐inflammatory Psoralen Derivatives ‐ Structures with Distinct Anti‐Inflammatory Activities

As a continuum to our work with coumarins, 12 psoralens were synthesized and evaluated for their anti‐inflammatory activity. Psoralens were prepared in three steps; at first, 7‐hydroxycoumarins were synthesized by von Pechmann condensation and then converted to 7‐(2‐oxopropoxy)coumarins. In the final step, a fused furan ring was introduced in an intramolecular ring‐formation reaction. Based on a SciFinder search, two out of the 12 synthesized psoralen derivatives (compounds 9 and 12) were found to be novel. The derivatives displayed anti‐inflammatory activity by suppressing iNOS and IL‐6 expression, but their mechanism of action seemed to be dependent on the substitution. Compound 6 with propyl side chain inhibited NF‐κB mediated transcription, while compound 10 with a phenyl substituent down‐regulated iNOS expression in a posttranscriptional manner. The results introduce psoralen derivatives as promising anti‐inflammatory compounds with potential for treatment of conditions involving iNOS and/or IL‐6‐mediated adverse responses.

Synthesis, anti-larvicidal and anti-bacterial studies of 7-hydroxy-4methylcoumarin, 7-acetoxy-4-methylcoumarin, 8-acetyl-7-hydroxy-4methylcoumarin, resacetophenone, 8-acetyl-5-hydroxy-4-methylcoumarin and 4, 7-dimethylcoumarin

The simple coumarins such as 7-hydroxy-4-methylcoumarin,7-acetoxy-4-methylcoumarin, 8-acetyl-7-hydroxy4-methylcoumarin, resacetophenone, 8-acetyl-5-hydroxy-4-methylcoumarin and 4, 7-dimethylcoumarin were synthesized by Von Pechmann condensation reaction of ethyleacetoacetate with phenols. The effect of synthesized coumarins on their anti-larvicidal and anti-microbial activities was studied. Out of six synthesized coumarins 7-hydroxy-4-methylcoumarin was found to show significant effect and inhibited the growth of the organism Escherchia Coli and the II instar and IV instar larvae of culex quinquefasciatus.

A solvent-free synthesis of coumarins using 1,3-disulfonic acid imidazolium hydrogen sulfate as a reusable and effective ionic liquid catalyst

1,3-Disulfonic acid imidazolium hydrogen sulfate has been used as an effective and reusable ionic liquid catalyst for the synthesis of coumarins from phenol derivatives with β-ketoesters via the Von Pechmann condensation under solvent-free conditions. This method consistently has the advantages of excellent yields, easy and quick isolation of the products, short reaction times, and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be recovered and reused for four times without loss of activity.

Recyclable CMK-5 supported sulfonic acid as an environmentally benign catalyst for solvent-free one-pot construction of coumarin through Pechmann condensation

Sulfonic acid modified nanostructured CMK-5 is used as an alternative to conventional acid catalysts in the von Pechmann condensation of a neat mixture of substituted phenols with ethyl acetoacetate leading to the formation of coumarin derivatives at 130°C. In comparison, CMK-5-SO3H showed a greater activity than some other homogeneous and heterogeneous catalysts. Additionally, the catalyst is reused repeatedly for 6 reaction cycles without any evidence of loss of activity, confirming the stability of the covalent bonding of acidic centers. The methodology presented offers reusable strategy for the efficient synthesis of coumarin, simplicity in operation, and green aspects by avoiding toxic conventional catalysts and solvents.

A facile synthesis of 2H-chromen-2-ones via Pechmann condensation under solvent free conditions using grinding technique

A simple and highly efficient procedure for the synthesis of 2H-chromen-2-ones via von Pechmann condensation, involving the grinding of different phenols and β-ketoesters in the presence of silica supported sulfuric acid at room temperature, under solvent free conditions, has been described.

Convergent, Fit-For-Purpose, Kilogram-Scale Synthesis of a 5-Lipoxygenase Inhibitor

Process research and development of a synthetic route towards a novel 5-lipoxygenase inhibitor is described. The synthetic route provided 1 in 27% yield in nine steps (seven steps in the longest linear sequence) and was performed on kilogram scale. The synthesis began with the preparation of the coumarin core via an efficient von Pechmann condensation. The triazole fragment was obtained via a regioselective copper-catalyzed [3 + 2] cycloaddition between a chiral alkyne and the coumarin azide.

ChemInform Abstract: Pentafluorophenylammonium Triflate (PFPAT): An Efficient, Metal‐Free and Reusable Catalyst for the von Pechmann Reaction

Abstractof phenols with β‐ketoesters (12 examples)

Pentafluorophenylammonium triflate (PFPAT): An efficient, metal-free and reusable catalyst for the von Pechmann reaction

Pentafluorophenylammonium triflate (PFPAT) is used as an efficient catalyst in the von Pechmann condensation of phenols with β-ketoesters leading to the formation of coumarin derivatives. Short reaction times, easy and quick isolation of the products, excellent chemoselectivity, excellent yields and ease of catalyst recovery with consistent activity makes this protocol efficient and environmentally benign.

Melamine trisulfonic acid as a new, efficient and reusable catalyst for the solvent free synthesis of coumarins

Melamine trisulfonic acid (MTSA) is easily prepared by the reaction between melamine and neat chlorosulfonic acid at room temperature. This compound can be used as an efficient and recyclable catalyst for the synthesis of coumarins via von Pechmann condensation reaction under solvent-free conditions.

Synthesis, Enzymatic Evaluation, and Docking Studies of Fluorogenic Caspase 8 Tetrapeptide Substrates

The synthesis, enzymatic evaluation, and molecular modeling studies of new fluorogenic tetrapeptide-based substrates selective for caspase 8, having the general structure Ac-IETD-AXX, are described. Various fluorescent reporter groups (AXX), i.e., 3- and 4-substituted coumarins and quinolin-2(1H)-ones were synthesized by von Pechmann condensation. They were subsequently coupled with the caspase-8-selective tetrapeptide Ac-IETD-OH under newly developed synthetic conditions to give the desired substrates in good yields and in high enantiomeric purity. Based on K(M) and V(max) values, the new compounds proved to be excellent substrates for recombinant human caspase 8. In contrast, the K(M) values for the same compounds as substrates for human caspase 3 were approximately 10-20-fold higher. Molecular modeling studies based on the X-ray crystal structures of both human caspases 3 and 8 revealed that there is sufficient room within both active sites to accommodate substrates with moderately bulky substituents in the 3- and 4-positions of the fluorogenic coumarins and quinolin-2(1H)-ones. Automated docking of the substrates into the active sites of both human caspases 3 and 8 with the program AutoDock 3 gave structures similar to the published crystallographic structures for the same tetrapeptide bound to caspase 8 in the form of an irreversible inhibitor. The calculated binding energies for the new substrates to either caspase 3 or 8 showed little difference between the substrates, consistent with the K(M) data. In addition, the calculated binding energies (DeltaG) to caspase 8 were considerably more negative than those to caspase 3, also consistent with the K(M) data. A possible molecular interaction that might explain the selectivity of the IETD tetrapeptide motif for caspase 8 over caspase 3 is discussed.

Ultrasound-promoted greener synthesis of 2H-chromen-2-ones catalyzed by copper perchlorate in solventless media

Copper perchlorate is found to be a heterogeneous catalyst for an efficient and greener synthesis of 4-substituted 2H-chromen-2-ones via von Pechmann condensation of substituted phenols and β-keto esters in solventless media with excellent yields using ultrasound irradiation. The present methodology offers several advantages such as excellent yields, simple procedure and milder conditions.

A Solvent-Free Synthesis of Coumarins Using Phosphotungstic Acid as Catalyst

Phosphotungstic acid (PTA) is used an efficient catalyst for the von Pechmann condensation reaction of phenols and β-keto esters under solvent-free conditions. This method was compared with those of the reactions in the different solvents and catalysts. The methodology presented offers significant improvements for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic conventional catalysts and solvents. Phosphotungstic acid (PTA) is used an efficient catalyst for the von Pechmann condensation reaction of phenols and β-keto esters under solvent-free conditions. This method was compared with those of the reactions in the different solvents and catalysts. The methodology presented offers significant improvements for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic conventional catalysts and solvents.

Scandium(III) Triflate–Catalyzed Coumarin Synthesis

Scandium(III) triflate is an excellent catalyst in the von Pechmann condensation. The solvent-free catalytic reactions proceed smoothly with a range of phenols and β-ketoesters in the presence of 10 mol% scandium(III) triflate at 80 °C. This simple method affords various 4-substituted coumarins in good to excellent yield and is superior to the classical method in several aspects: solvent-free conditions, short reaction times, a decreased catalyst loading, a mild reaction temperature, and an easy workup.

A Convenient Synthesis of Some Coumarin Derivatives Using SnCl2 · 2H2O as Catalyst

Some substituted coumarins have been synthesized by von-Pechmann condensation using SnCl2 · 2H2O (10 mol %) as catalyst in ethanolic medium. The reactions are simple, easy in handling and environmentally benign.

Iodine a Simple, Effective and Inexpensive Catalyst for the Synthesis of Substituted Coumarins

Molecular iodine is developed as an efficient catalyst in the von Pechmann condensation of phenols with b-ketoesters which leads to the formation of coumarin derivaties in excellent yields when carried out under microwave irradiation in a Prolabo Synthwave Microwave Reactor. The reaction also proceeds when carried out in the absence of solvent and at room temperature in acetonitrile.

Benzylsulfonic acid functionalized mesoporous Zr-TMS catalysts: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Benzylsulfonic acid functionalized mesoporous Zr-TMS (Zr-TMS-BSA, Zr-TMS, zirconia based transition metal oxide mesoporous molecular sieves) catalyst is used as an alternative to conventional acid catalysts in the von Pechmann condensation of aromatic alcohols with ethyl acetoacetate leading to the formation of coumarin derivatives in solvent free condition at 150 °C. Three types of coumarins, 7-hydroxy-4-methylcoumarin (β-methylumbelliferone), 7-methoxy-4-methylcoumarin (Methyl-4-methylumbelliferyl ether) and 7,8-benzo-4-methylcoumarin derivatives have been prepared using resorcinol, 3-methoxyphenol and 1-naphthol, respectively. The catalytic activity and the recycle studies of the catalyst in all the three reactions proved the superior performance of the catalyst. Further the products were confirmed by GC, elemental analysis, melting point and NMR techniques. Finally, the probable mechanism for Pechmann condensation using Zr-TMS-BSA catalyst has been reported.

Chlorosulfonic acid-catalysed one-pot synthesis of coumarin

Chlorosulfonic acid is used as an alternative to conventional acid catalysts in the von Pechmann condensation of phenol with β-ketoester leading to the formation of substituted coumarin.

Samarium(III)‐Catalyzed One‐Pot Construction of Coumarins.

AbstractFor Abstract see ChemInform Abstract in Full Text.